Here’s what we know:

—Orlando’s mayor says Omar Mateen threatened to strap explosives onto his hostages at the Pulse nightclub. He also said the attacker drove around several locations in the city before killing 49 people at Pulse, a gay nightclub.

—News reports say Mateen’s wife might have been aware of the plot to attack Pulse. She told federal agents she tried to talk him out of Sunday’s attack. The U.S. attorney declined to say if anyone would be charged in the attack.

—President Obama said at present investigators “do not have any information to indicate that a foreign terrorist group directed the attack in Orlando.” But, he added, it’s clear Mateen was radicalized over the Internet.

—Follow the developing story below. All updates are in Eastern Standard Time.

Updated on June 15 at 3:34 p.m.

Mateen’s movements

The FBI sought the public’s help Wednesday to construct what led Omar Mateen to select the Pulse nightclub as the target of his attack on Sunday.

‘‘We need your help in developing the most complete picture of what he did and why he did it,’’ FBI agent Ron Hopper said at a news conference.

Lee Bentley, the U.S. attorney, declined to comment on whether charges would be brought against anyone in the case, merely saying investigators were talking to several other people in connection with the attack that killed 49 people. On Tuesday, news reports said Mateen’s wife, Noor Zahi Salman, helped him scout the Pulse nightclub.

Buddy Dyer, the Orlando mayor, said Mateen drove around several locations in the Orlando area Saturday evening, before he picked Pulse.

“What I know concretely is that he was driving around that evening and visited several locations,” Dyer said. He did not elaborate.

And, Dyer said, Mateen had threatened to strap explosives onto the hostages, hastening the decision to send a SWAT team to the location to end the standoff.

“We had independent verification of that,”  Dyer said. “We had a lot of information from the inside and they independently were saying yes, the bomber is about to put on an explosive vest.”

It’s unclear, however, whether Mateen actually possessed explosives at the time.

7:13 p.m. ET

What did Omar Mateen’s wife know?

NBC and others are reporting Omar Mateen’s wife, Noor Zahi Salman, might have been aware of the plot to attack Pulse. She told federal agents she tried to talk him out of Sunday’s attack, NBC reported.

Here’s more:

Omar Mateen's wife, Noor Zahi Salman, told the FBI she was with him when he bought ammunition and a holster, several officials familiar with the case said. She told the FBI that she once drove him to the gay nightclub, Pulse, because he wanted to scope it out. …

Authorities are considering filing criminal charges against Noor for failing to tell them what she knew before the brutal attack, law enforcement officials say, but no decision has been made.

News reports say she is cooperating with investigators.

12:50 p.m.

Obama addresses terrorism

The president, speaking at the White House, reiterated some of what we already know about Omar Mateen.

“We currently do not have any information to indicate that a foreign terrorist group directed the attack in Orlando,” he said. “It is increasingly clear, however, that the killer took in extremist information and propaganda over the internet. He appears to have been an angry, disturbed, unstable young man who became radicalized.”

Obama said lone-wolf actors like Mateen are hard to detect, but “we are doing everything in our power to stop these kinds of attacks.

“We work to succeed 100 percent of the time,” Obama said. “The attacker, as we saw in Orlando, only has to succeed once.”

Obama also took the opportunity to rail against the proposal by Donald Trump, the presumptive Republican presidential nominee, to temporarily ban Muslim immigration to the U.S.

“The Orlando killer, one of the San Bernardino killers, the Fort Hood killer, they were all U.S. citizens,” Obama said. “Are we going to start treating all Muslim Americans differently? Are we going to start subjecting them to special surveillance? Are we going to start discriminating them because of their faith? We’ve heard these suggestions during the course of this campaign. Do republican officials actually agree with this? Because that’s not the america we want.”

We’ll have a story on Obama’s full remarks presently, and will provide a link to it here.

Updated on June 14 at 7:03 a.m.

Morning headlines

Here are some of the headlines we’re seeing this morning on the attack in Orlando:

Omar Mateen, an ‘Americanized Guy,’ Shows Threat of Lone Terrorists (The New York Times)

Witness: Omar Mateen drank alone at Pulse before attack (The Orlando Sentinel)

What ISIS Wants (The Atlantic)

Meanwhile, the city Orlando has identified all 49 victims of the shooting at Pulse, a gay nightclub in the city.

6:11 p.m.

‘America’s Bataclan’

French and American media are drawing comparisons between the shooting at the nightclub and the terrorist attack at the Bataclan concert hall in Paris last year, in which 89 people were killed. Like in Paris, the victims of the Orlando massacre were mostly young people in their twenties and thirties, enjoying a night out. Like at the Bataclan, witnesses of the Orlando rampage initially thought the sounds of gunshots were part of the club’s music.

“At first it sounded like it was part of the show, because there was an event going on —we were all just having a good time,” Andy Moss, who was inside the club, told CNN. “But once people started screaming and shots just kept ringing out, you know that it’s not a show any more, and you gotta do what you’ve gotta do ... My first instinct was to run and get out.”

CNN also reported first responders heard the ringing of cellphones when they entered the nightclub after the shooting, the sounds of the relatives and friends of the victims trying to reach them. “That was, of course, the same at Bataclan,” French journalist Anne-Elisabeth Moutet told the BBC. “That was one of the shocks that police came across.”

3 p.m.

Donald Trump sounds off

The presumptive Republican presidential nominee in a speech that’s still going on said: “The only reason the killer was in America in the first place is because we allowed his family to come here.”

Trump used the occasion to criticize Hillary Clinton, his likely Democratic rival in November, as well as President Obama. He called Clinton’s immigration policy “radical” and said he wants one that “promotes American values.”

Earlier this morning, Trump appeared to suggest that Obama was somehow involved in the shooting. “He doesn’t get it or he gets it better than anybody understands—it’s one or the other and either one is unacceptable,” he said.

My colleague David Graham is watching Trump’s remarks and we’ll update this with more from Trump’s speech.

2:53 p.m.

Remembering the victims

The bodies of the victims were removed from the Pulse nightclub late Sunday night, and authorities spent Monday identifying the dead and notifying their families. Florida Attorney General Pam Bondi told CNN Monday afternoon that interpreters have been brought in to speak to relatives because many speak only Spanish.

The city of Orlando has created a page on its website with a list of the victims’ names and their ages. So far, 46 of the 49 victims have been identified. The majority of the victims are men in their twenties and thirties. The youngest was 19, the oldest was 50. Here is the full list:

Edward Sotomayor Jr., 34 years old

Stanley Almodovar III, 23 years old

Luis Omar Ocasio-Capo, 20 years old

Juan Ramon Guerrero, 22 years old

Eric Ivan Ortiz-Rivera, 36 years old

Peter O. Gonzalez-Cruz, 22 years old

Luis S. Vielma, 22 years old

Kimberly Morris, 37 years old

Eddie Jamoldroy Justice, 30 years old

Darryl Roman Burt II, 29 years old

Deonka Deidra Drayton, 32 years old

Alejandro Barrios Martinez, 21 years old

Anthony Luis Laureanodisla, 25 years old

Jean Carlos Mendez Perez, 35 years old

Franky Jimmy Dejesus Velazquez, 50 years old

Amanda Alvear, 25 years old

Martin Benitez Torres, 33 years old

Luis Daniel Wilson-Leon, 37 years old

Mercedez Marisol Flores, 26 years old

Xavier Emmanuel Serrano Rosado, 35 years old

Gilberto Ramon Silva Menendez, 25 years old

Simon Adrian Carrillo Fernandez, 31 years old

Oscar A Aracena-Montero, 26 years old

Enrique L. Rios, Jr., 25 years old

Miguel Angel Honorato, 30 years old

Javier Jorge-Reyes, 40 years old

Joel Rayon Paniagua, 32 years old

Jason Benjamin Josaphat, 19 years old

Cory James Connell, 21 years old

Juan P. Rivera Velazquez, 37 years old

Luis Daniel Conde, 39 years old

Shane Evan Tomlinson, 33 years old

Juan Chevez-Martinez, 25 years old

Jerald Arthur Wright, 31 years old

Leroy Valentin Fernandez, 25 years old

Tevin Eugene Crosby, 25 years old

Jonathan Antonio Camuy Vega, 24 years old

Jean C. Nives Rodriguez, 27 years old

Rodolfo Ayala-Ayala, 33 years old

Brenda Lee Marquez McCool, 49 years old

Yilmary Rodriguez Sulivan, 24 years old

Christopher Andrew Leinonen, 32 years old

Angel L. Candelario-Padro, 28 years old

Frank Hernandez, 27 years old

Paul Terrell Henry, 41 years old

Antonio Davon Brown, 29 years old

Interviews with relatives and friends have provided a glimpse into the lives of some of the victims. WFTV, the ABC affiliate in Orlando, spoke to Robert Guerrero, the cousin of Juan Ramon Guerrero, one of the victims. Robert Guerrero said his cousin came out as gay earlier this year. More from WFTV:

Robert Guerrero said his cousin worked as a telemarketer and in recent months he started attending college at the University of Central Florida. Guerrero said his cousin didn't quite know what he wanted to study, but he was happy to be in school. And he was happy in a relationship with a person his relatives came to regard as a member of the family, Guerrero said.

“He was always this amazing person (and) he was like a big brother to me,” he said of his cousin. “He was never the type to go out to parties, would rather stay home and care for his niece and nephew.”

The Tampa Bay Times spoke to Rosalia Ramos, the mother of Stanley Almodovar. Ramos had made her son tomato-and-cheese dip to eat after he returned from Pulse. More:

“My son passed away,” she said. “I didn’t eat, I didn’t sleep. I went to the hospital to see my son.”

Ramos said she moved herself and her children from Puerto Rico to Florida. She said she does not know how to go forward.

“I don't know what I'm going to do tomorrow,” she said, adding that her son's car was still in Orlando. “I don't know nothing.”

2:16 p.m.

Mateen’s father speaks

Seddique Mateen Mir, speaking to reporters at his home in Port St. Lucie, Florida, earlier Monday:

Yesterday I was in shock, my whole family was in shock. I don’t approve of what he did. What he did was an act of terrorism.

Here are more of his remarks, via The New York Times: “The United States is my home and it has always taken care of me and my family. wish I knew what he was doing. I would have arrested him myself.”

2:06 p.m. EST

Forty-five of 49 victims identified

The City of Orlando has named all but four of the victims in Sunday’s attack. Full list here.

1:31 p.m.  

Hillary Clinton gives her first speech since the shooting

The presumptive Democratic presidential nominee described the Orlando shooter as a “lone wolf.” The threat of ISIS is “metastasizing,” Clinton said. “We saw this in Paris and we saw it in Brussels. We face a twisted ideology and poisoned psychology that inspires the so-called lone wolves, radicalized individuals who may or may not have contact and direction from any formal organization.”

Clinton began her remarks by saying “today is not a day for politics,” but minutes later she began to list several prescriptions for combating ISIS abroad and gun violence on U.S. soil. Here’s an excerpt:

We may have our disagreements about gun-safety regulations, but we should all be able to agree on a few essential things. If the FBI is watching you for suspected terrorist links, you shouldn't be able to just go buy a gun with no questions asked.

Clinton was referring to the fact that the shooter, Omar Mateen, was placed on an FBI terrorism watch list in 2013 and 2014 when the agency investigated him for potential ties to terrorism. Mateen was not on a watch list at the time of the shooting. The guns Mateen used in the shooting were purchased legally.

1:10 p.m.

FBI Director James Comey in a news conference detailed what investigators have learned about Mateen. “There are strong indications of radicalization by this killer and a potential of inspiration by foreign terrorist organizations,” Comey said.

Comey purposely did not use Mateen’s name throughout his remarks, saying  “part of what motivates sick people to do this kind of thing is some twisted notion of fame or glory, and I don’t want to be part of that for the sake of the victims and their families, and so that other twisted minds don’t think that this is a path to fame and recognition.”

He said investigators are examining Mateen’s electronic devices. He said there is no indication so far that Mateen received instruction from abroad or was part of a terrorist network. Mateen was “radicalized, and at least, in some part, through the internet.” Investigators are “working to understand what role anti-gay bigotry played in motivating this attack,” he said.

“We are looking for needles in a nationwide haystack,” Comey said. “But were also called upon to figure out which pieces of hay that someday become needles.”

Comey said Mateen first came to the attention of FBI in May 2013, when he worked as a security guard at a local courthouse. Mateen had told his coworkers he was a member of terrorist group Hezbollah, his family had ties to al-Qaeda, and he told coworkers that “he hoped law enforcement would raid his apartment and assault his wife and child so he could martyr himself.” The FBI spent 10 months investigating him, which including interviewing him twice, following him, recording his conversations with informants, and surveilling his communications. Mateen said he made those remarks because he felt his coworkers were discriminating against him for being Muslim, and the investigation was dropped.

The FBI looked into him again in July of 2014, when they learned Mateen and the American suicide bomber who died in Syria attended the same mosque in Florida.

Comey also gave more details of the phone calls the shooter made to 911 dispatchers during Sunday’s attack. Mateen dialed 911 twice. The dispatcher called him back after that, and then Mateen pledged loyalty to Abu Bakr al-Baghdadi, the leader of ISIS, and expressed solidarity with the bombers of the 2013 Boston Marathon and an American citizen who carried out a suicide bombing in Syria in 2014.

11:26 a.m.

President Obama says it appears Omar Mateen was radicalized by extremist propaganda disseminated on the Internet. Here’s an excerpt from his remarks at the White House made after he received a security briefing:

We’re still at the preliminary stages of the investigation, and there’s a lot more that we have to learn. The one thing that we can say is that this is being treated as a terrorist investigation. It appears that the shooter was inspired by various extremist information that was disseminated on the Internet. All those materials are currently being searched, exploited so we can have a better sense of the pathway that the killer took in making a decision to launch this attack.  … At this stage, we see no clear evidence that he was directed externally. It does appear that at the last minute he pronounced allegiance to ISIL, but there’s no evidence so far that he was, in fact, directed by ISIL, and there are also, at this stage, no direct evidence that he was part of a larger plot. In that sense, it appears to be similar to what we saw in San Bernardino, but we don’t yet know.

The president’s remarks also touched on gun control, the Islamic State, and violence against the LGBT community.

10:06 a.m.

Omar Mateen’s former wife, Sitora Yusufiy, is speaking to reporters about the Orlando gunman, recalling his “instability” and his violence toward her.

Here’s what she said about Mateen, via USA Today:

In the beginning he was a normal being that cared about family, loved to joke, loved to have fun. But then, a few months after we were married, I saw his instability and I saw that he was bipolar and he would get mad out of nowhere. That’s when I started worrying about my safety.

Yusufiy’s family extricated her from her marriage when Mateen became violent toward her, she said, and they no longer were in contact.

Asked to explain his violent outburst on Sunday, she suggested, “emotional instability. Sickness. He was mentally unstable and mentally ill — that’s the only explanation that I could give. And he was obviously disturbed, deeply, and traumatized.”

8:48 a.m.

The Orlando Police Department has revised the death toll in Sunday’s shooting at Pulse, a gay nightclub in the city, to 49. The 50th body belonged to the shooter, Omar Mateen, the department said.

Forty-eight of the 49 victims have been identified, the department said, and the next of kin of 24 of the victims have been notified. At a news conference Monday, which was tweeted by the department, Chief John Mina described what happened at Pulse early Sunday morning:

5:52 a.m.

Good morning. New details are emerging about Omar Mateen, the man who killed 50 people and wounded 53 others at the Pulse nightclub in Orlando.

Here’s how The New York Times begins its story:

Omar Mateen’s life seemed to be on a successful trajectory a decade before he carried out one of the worst cases of mass murder in American history.

He earned an associate degree in criminal justice technology in 2006. A year later, he was hired by one of the world’s premier private security companies, G4S. And then, in 2009, he got married and bought a home.

Soon, though, signs of troubles emerged.

We are also learning the names of more of the victims at the popular gay nightclub. The City of Orlando says it will update the list as the families of the victims are notified.

Meanwhile, the Islamic State radio called Mateen “one of the soldiers of the caliphate in America.” What that means isn’t exactly clear: We don’t know if Mateen was affiliated with the group or inspired by it.  

June 12, 10:26 p.m.

We're signing off for the night. Coverage will resume at 6 a.m. Monday morning.

10:17 p.m.

Santa Monica Police Chief Jacqueline Seabrooks says earlier reports that a man arrested earlier today in Los Angeles intended to harm the L.A. Pride Festival were inaccurate.

The Los Angeles Times has more:

Santa Monica Police Chief Jacqueline Seabrooks initially said on Twitter that the 20-year-old man told one of her officers after he was arrested that he wanted “to harm Gay Pride event.”

But Lt. Saul Rodriguez said later the tweet was a misstatement. He said the suspect told investigators that he was going to the Pride festival but said he did not make additional statements about his intentions.

"It was a misstatement," Rodriguez said. "Unfortunately, she was given incorrect information initially, which indicated that that statement was made; however, that statement never was made. He did indicate that he was planning on going to the Pride festival but beyond anything as far as motives or his intentions that statement was never made nor did any officer receive that statement.”

8:14 p.m.

Host James Corden opened tonight’s Tony Awards in New York City on a somber note by paying tribute to the Orlando shooting victims.

All around the world, people are trying to come to terms with the horrific events that took place in Orlando this morning. On behalf of the whole theater community and every person in this room, our hearts go out to all of those affected by this atrocity. All we can say is you are not on your own right now. Your tragedy is our tragedy. Theater is a place where every race, creed, sexuality, and gender is equal, is embraced, and is loved. Hate will never win. Together, we have to make sure of that. Tonight’s show stands as a symbol and a celebration of that principle.

The New York Daily News reported that the cast of "Hamilton," a popular Revolutionary War musical, won't use muskets in their performance during tonight's ceremonies out of respect for the victims.

6:57 p.m. ET

Donald Trump's condolence message also took aim at his likely Democratic opponent Hillary Clinton. In a statement, the Clinton campaign fired back against him and his comments on the shooting.

5:42 p.m.

In New York City, two towers will make two different tributes tonight.

New York Governor Andrew Cuomo announced Sunday afternoon that One World Trade Center will “be lit [in] the colors of the pride flag in a tribute to LGBT Americans and the lives that were lost.”

At the same time, the Empire State Building announced its upper floors will not be lit at all in memory of the deceased.

5:19 p.m.

Presumptive Republican presidential nominee Donald Trump offering his condolences. He also said President Obama “should step down” and his likely Democratic rival Hillary Clinton “should get out of this race for the Presidency” for not calling the attacks “radical Islamic terrorism.”

He added:

If we do not get tough and smart real fast, we are not going to have a country anymore. Because our leaders are weak, I said this was going to happen – and it is only going to get worse. I am trying to save lives and prevent the next terrorist attack. We can't afford to be politically correct anymore.

The terrorist, Omar Mir Saddique Mateen, is the son of an immigrant from Afghanistan who openly published his support for the Afghanistani Taliban and even tried to run for President of Afghanistan. According to Pew, 99% of people in Afghanistan support oppressive Sharia Law.

We admit more than 100,000 lifetime migrants from the Middle East each year. Since 9/11, hundreds of migrants and their children have been implicated in terrorism in the United States.

Hillary Clinton wants to dramatically increase admissions from the Middle East, bringing in many hundreds of thousands during a first term – and we will have no way to screen them, pay for them, or prevent the second generation from radicalizing.

We need to protect all Americans, of all backgrounds and all beliefs, from Radical Islamic Terrorism - which has no place in an open and tolerant society. Radical Islam advocates hate for women, gays, Jews, Christians and all Americans. I am going to be a President for all Americans, and I am going to protect and defend all Americans. We are going to make America safe again and great again for everyone.

Trump added that he planned to make a “major speech” on foreign policy on Monday. He did not acknowledge that the victims were members of the LGBT community.

In a subsequent tweet, Trump also seemed to reference his proposed ban on Muslim immigration, which he first suggested last December after the San Bernardino shootings.

In May, Trump said the ban was “just a suggestion.” Mateen was born in New York.

5:03 p.m.

Democratic presidential contenders Hillary Clinton and Bernie Sanders have both offered their condolences to the victims in Orlando. Clinton’s statement focused on terrorism, the LGBT community, and gun control:

I join Americans in praying for the victims of the attack in Orlando, their families and the first responders who did everything they could to save lives.  

This was an act of terror.  Law enforcement and intelligence agencies are hard at work, and we will learn more in the hours and days ahead.  For now, we can say for certain that we need to redouble our efforts to defend our country from threats at home and abroad.  That means defeating international terror groups, working with allies and partners to go after them wherever they are, countering their attempts to recruit people here and everywhere, and hardening our defenses at home. It also means refusing to be intimidated and staying true to our values.

This was also an act of hate.  The gunman attacked an LGBT nightclub during Pride Month.  To the LGBT community: please know that you have millions of allies across our country.  I am one of them.  We will keep fighting for your right to live freely, openly and without fear.  Hate has absolutely no place in America.

Finally, we need to keep guns like the ones used last night out of the hands of terrorists or other violent criminals.  This is the deadliest mass shooting in the history of the United States and it reminds us once more that weapons of war have no place on our streets.  

This is a time to stand together and resolve to do everything we can to defend our communities and country.

Sanders’ statement touched on the same themes. He issued it before President Obama and the FBI said they believed the shooting was an act of terror:

All Americans are horrified, disgusted and saddened by the horrific atrocity in Orlando.

At this point we do not know whether this was an act of terrorism, a terrible hate crime against gay people or the act of a very sick person, but we extend our heartfelt condolences to the victims’ families and loved ones and our thoughts are with the injured and the entire Orlando LGBTQ community.

4:29 p.m.

The city of Orlando is posting the names of victims whose families have been notified on the city website. Only four names have been released so far.

3:21 p.m.

FBI Special Agent Ronald Hopper definitively identified the gunman as 29-year-old Omar Mateen at an afternoon press conference. He said Mateen died in an exchange of gunfire at the Pulse nightclub. Mateen, who was born in New York, was an American citizen of whom the bureau had been aware since 2013, Hopper said. He’d been investigated and questioned in 2013 and 2014, but the FBI didn’t find enough to merit a continued investigation of Mateen, Hopper said.

Hopper said Mateen had made 911 calls before his death. He declined to elaborate on the content of those calls, but said they had “become federal evidence [and] ...it was general to the Islamic State.” News reports had previously said Mateen had in the 911 calls pledged allegiance to ISIS, as the group is also known.

Trevor Velinor, an assistant special agent from the Bureau of Alcohol, Tobacco, Firearms, and Explosives, said Mateen had legally purchased both of the weapons used in the attack in the past few days.

3:05 p.m.

The Islamic State has claimed responsibility for the attack, via its Amaq news agency.

To put this in context, we’ll turn to Rukmini Callimachi, The New York Times reporter, who has been tweeting about the attacks:

3:04 p.m.

The U.K. royal family says it is shocked by the killings. Here’s a tweet from its official account:

2:59 p.m.

CNN and others are reporting that Omar Mateen, the man named by several news organizations and a U.S. congressman as being responsible for the shooting, worked as a security guard for G4S Secure Solutions. Here’s a statement from the firm, via CNN:

We are shocked and saddened by the tragic event that occurred at the Orlando nightclub. We can confirm that Omar Mateen had been employed with G4S since September 10, 2007. We are cooperating fully with all law enforcement authorities, including the FBI, as they conduct their investigation. Our thoughts and prayers are with all of the friends, families and people affected by this unspeakable tragedy.   

2:58 p.m.

Here’s Canadian Prime Minister Justin Trudeau’s reaction:

2:16 p.m.

“Today marks the most deadly shooting in American history,” President Obama said as he addressed the nation from the White House. He stressed the FBI’s investigation was just beginning and he offered no details on the attacker’s motives or associations. “Although it is early in the investigation, we know enough to say this is an act of terror and an act of hate,” he said.

He added:

We are still learning all the facts. This is an open investigation We’ve reached no definitive judgment on the precise motivations of the killer. The FBI is appropriately investigating this as an act of terrorism, and I’ve directed that we spare no effort to determine what, if any, inspiration or association this killer may have had with terrorist groups. What is clear is that he was a person full of hatred.

While paying tribute to the victims, the president also noted the singular role of gay bars and nightclubs in the LGBT community, describing them as “a place of solidarity and empowerment, where people have come together to raise awareness, to speak their minds, and to advocate for their civil rights.”

While Obama did address gun violence in general, he spoke with a sense of resignation about the intractable debate over gun control. “This massacre is … a further reminder of how easy it is for someone to get their hands on a weapon that let's them shoot people in a school, or in a house of worship, or a movie theater, or in a nightclub,” he said. “And we have to decide if that's the kind of country we want to be. And to tactically do nothing is a decision as well.”

“In the face of hate and violence, we will love one another,” Obama said. “We will not give in to fear and turn against each other.”

1:52 p.m.

Pope Francis condemned “this new manifestation of homicidal folly and senseless hatred” in a statement about the Orlando shootings, Vatican Radio said.

“Pope Francis joins the families of the victims and all of the injured in prayer and in compassion,” the Vatican’s statement said. “Sharing in their indescribable suffering he entrusts them to the Lord so they may find comfort.”

1:32 p.m.

The Los Angeles Times is reporting a man with guns and possible explosives was arrested in Santa Monica on Sunday. He reportedly told police he was going to the city’s gay-pride rally. Hillary Clinton, the presumptive Democratic presidential nominee, is scheduled to take part in the celebrations in LA. Several cities around the U.S., including Boston and Washington, D.C., held gay-pride celebrations this weekend. Here’s a complete list.

1:27 p.m.

Sunday’s shooting comes during LGBT Pride Month, and law-enforcement agencies in major U.S. cities are stepping up their presence at LGBT sites and events. District of Columbia Mayor Muriel Bowser said D.C. police will bolster their presence this weekend at Capitol Pride, the region’s annual LGBT-pride event, during Sunday’s festival.

In New York City, the NYPD said it placed its patrol and counter-terrorism units on alert. A New York Daily News reporter tweeted that armed NYPD officers have been placed outside the historic Stonewall Inn.

12:24 p.m.

Florida Governor Rick Scott has declared a state of emergency in Orange County, freeing up more state law-enforcement resources to assist in Orlando.

Addressing reporters in Orlando, Scott said the state “would provide all the resources anyone needs” in response to the shooting.

12:12 p.m.

President Obama will make a statement about the Orlando shooting at 1:30 p.m. ET, the White House says. Vice President Joe Biden has also canceled his planned appearance at a campaign fundraiser in Florida tonight.

11:31 a.m.

OneBlood, a blood-donation organization in Orlando, is asking for donations on its Twitter feed:

But gay men, under current FDA rules, will be unable to donate blood to those in need after the attack.

10:26 a.m.

Mayor Buddy Dyer said 50 people have been killed and 53 others taken to local hospitals.

“There’s blood everywhere,” he said at a news conference, adding the shooter used an assault rifle during the attack. He said he had asked the governor to declare a state of emergency.

Orlando Police Chief John Mina said a handgun and an AR-15-type assault rifle was recovered from the scene. He said an unknown number of rounds were fired.

FBI said the investigation was in its early stages, and the bureau was investigating all angles, including whether it was a hate crime and if it was terrorism.

Imam Muhammad Musri, president of American Islam and the Islamic Society of Central Florida, urged the media not to rush to judgment. “It’s our worst nightmare, and we are sorry to know it happened to us,” he said.

10:19 a.m.

Congressman Alan Grayson, Democrat of Florida, at a news conference identified the shooter as Omar Mateen. He said Mateen was in his late 20s. He said the gunman was a U.S. citizen, but that is “not true of some of his family members.” Grayson’s congressional district includes part of Orlando.

10:01 a.m.

USA Today has more on Pulse, the club where the attack took place, and which labels itself as “not just another gay club.” An excerpt:

One of the owners of the gay nightclub where multiple people were shot early Sunday in Orlando started the club to promote awareness about the area's lesbian, gay, bisexual and transgender community. Her brother died from AIDS.

Barbara Poma opened Pulse on Orange Avenue in Orlando with her friend and co-founder Ron Legler in 2004. It hosts nightly themed performances as well as a monthly program of LGBT-related educational events.

9:42 a.m.

Multiple news organizations, including CBS News and NBC, citing anonymous law-enforcement sources, have identified the suspect as Omar Mateen, 27, of Port St. Lucie, Florida. We have not independently confirmed their reporting.

9:27 a.m.

The presumptive Republican and Democratic presidential nominees shared their thoughts:

9:24 a.m.

Florida’s governor responds to the attack:

9:19 a.m.

The White House says President Obama has been briefed on the attack.

7:14 a.m.

Multiple people have been killed and at least 42 people are being treated at local hospitals after a gunman opened fire and took hostages at a gay nightclub in Orlando, Florida, early Sunday, police said. The gunman is dead.

At a news conference Sunday, Orlando Police Chief John Mina said “multiple people are dead inside” the Pulse nightclub in downtown Orlando, but he declined to provide an exact number, saying the number was about 20. Forty-two people have been transported to local hospitals, he said. Mayor Buddy Dyer called it a “crime that will have a lasting effect on our community.” Orange County Sheriff Jerry Demings, at the same news conference, called it a “domestic terror incident,” and an FBI official said there are “suggestions that the individual may have leanings towards (Islamist) ideology,” but he added the bureau was pursing other angles as well.

Here’s what happened, in Mina’s words:

At approximately 0202 hours this morning, we had an officer working at Pulse nightclub, who responded to shots fired. Our officer engaged in a gun battle with that suspect. That suspect at some point went back inside the club, where more shots were fired. This did turn into a hostage situation. Obviously multiple officers from various agencies responded, SWAT team responded. At approximately 0500 hours this morning, the decision was made to rescue hostages that were in there."

The shooter was found dead inside the club, Mina said. One officer was lightly injured, he said.

The shooter had an assault-type rifle, a handgun, and some type of device on him, he said. Officials at the news conference described the gunman as well-prepared and well-organized. He was not from the area, they said.

Earlier, the Orlando Police tweeted:

Pulse is a popular nightspot that hosts what it calls “Upscale Latin Saturdays” with three DJs and a show a midnight. On its Facebook page, the club warned customers to “get out of pulse and keep running.” A subsequent message said:

As soon as we have any information we will update everyone. Please keep everyone in your prayers as we work through this tragic event. Thank you for your thoughts and love.

The shooting comes a little more than a day after a gunman shot and killed Christina Grimmie, the singer, at a concert venue in the city. Officials at the news conference said the two incidents were not connected.