People lay toys and flowers for victims of the Russian plane crash outside of Pulkovo airport in St. Petersburg on Sunday.Reuters

Russians observed a day of mourning on Sunday for the 224 people killed in a passenger plane crash in Egypt on Saturday.

People placed flowers and toys at the entrance of Pulkovo Airport in St. Petersburg, where the airliner was headed when it departed from Sharm el-Sheikh, located in the southern part of the Sinai Peninsula, early Saturday morning. The plane crashed about 23 minutes after takeoff, in a remote, mountainous area of the Sinai.

Russian President Vladimir Putin declared a nationwide day of mourning to last three days. Flags across the country are flying at half-staff. The government has said it would pay compensation to the victims’ families and help organize funerals, according to the Associated Press. In Cairo, people lined the walls of the Russian embassy with flowers.

The cause of the crash is not yet known. A Russian aviation official said Sunday that the plane “broke up in mid-air” before it went down in the Hassana area of the Sinai, the BBC reported. The aircraft was flying at an altitude of about 30,000 feet when it disappeared from flight-tracking systems. Egyptian aviation officials say the pilot had reported technical difficulties and was planning to land the Airbus A321-200 at the nearest airport before losing contact with air traffic controllers. Russian officials dismissed a claim by a local affiliate of the Islamic State that it “brought down” the plane. Preliminary reports suggest technical malfunctions. From The New York Times:

The wife of the co-pilot of the Airbus that crashed told Russia’s NTV channel that her husband had complained about the mechanical condition of the plane, operated by Kogalymavia, a private company flying planes under the name Metrojet. The woman, Natalya Trukhacheva, told the station that her husband had said “before the flight that the technical condition of the airplane left much to be desired.”

On Sunday, the newspaper Izvestia reported that the airline had fallen into financial difficulties recently and owed money to a pension fund. A spokeswoman for the airline said on Saturday that its planes had undergone regular maintenance and were flown by experienced pilots.

Rescue teams reached the crash site hours after the crash. By Sunday morning, about 163 bodies had been moved to Egyptian morgues. Egyptian authorities have begun transporting bodies by ambulance to airports to be flown to Russia. Russian authorities have collected DNA samples from 140 relatives to help in identifying the victims, the Times reported. Inspectors recovered the aircraft’s “black boxes,” which record flight data and audio within the pilot’s cockpit. Russia has established a state commission to investigate the crash.

The 217 passengers included 138 women, 62 men, and 17 children. All were Russian except for four Ukrainians and one Belarusian. The seven crew members aboard were all Russian. Many were families on vacation on Sharm el-Sheikh’s beaches on the Red Sea, a popular tourist spot in wintertime.

Russia’s air-safety regulator has ordered Metrojet, the company that operated the plane, to suspend all flights of its Airbus aircraft. Air France, Lufthansa, and Emirates airlines have rerouted flights to avoid the Sinai Peninsula until officials determine there’s no risk of surface-to-air missile attacks. In July 2014, a Russian-made missile brought down Malaysia Airlines Flight 17 over eastern Ukraine, killing all 298 people aboard.

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