CAIRO -- When General Abdel Fattah al-Sisi, head of Egypt's armed forces, called for the military's supporters to take to the streets on Friday and provide him with "a mandate to confront possible violence and terrorism," unrest seemed inevitable.
Hundreds of thousands of protesters heeded Sisi's call, converging on Cairo's Tahrir Square, waving Egyptian flags, clambering on tanks for photo opportunities, and cheering wildly when military helicopters buzzed the crowd.
"Once the military starts building its powers, they will not just be used against the Muslim Brotherhood, but against all social movements."
Meanwhile, across town, security forces fired on counter-demonstrators in what became the worst mass killing since Hosni Mubarak's dictatorial regime was overthrown in 2011.
Supporters of Egypt's first democratically elected president, Mohammed Morsi -- who was ousted by the military on July 3 -- massed at Rabaa al-Adawia mosque to demand his reinstatement.
Demonstrators moved out from the mosque, which has been at the center of a sit-in since Morsi was removed from power, and attempted to march across nearby October Sixth bridge. There, eye witnesses say, they were met by security forces backed by armed men in civilian clothes, who attacked them with tear gas and birdshot. Later, they used live fire. The intent appeared to be to use lethal force against protesters reported to be armed with little more than rocks, fireworks, and spent tear gas canisters.
At least 74 were killed, according to Human Rights Watch, while doctors who had treated the casualties in the makeshift hospital behind the mosque put the toll at as many as 120 and hundreds more injured. It was the second mass killing within a month after 51 Muslim Brotherhood supporters were killed in the July 3rd Republican Guard's club shooting.
At the makeshift field hospital behind Rabaa mosque, doctors said that most of those killed died from bullet wounds to the head, neck, and torso. Dr. Mohammad Elatfy, who lives and works in Manchester, was in Cairo visiting family when he saw an appeal for doctors on local television. He arrived shortly after 5 a.m., when the casualties were beginning to overwhelm the underequipped facility. "I treated one man shot in the leg, one in the chest and one in the neck. There were three dead one the floor in front of me, with bullets in their heads," he said. "I'll never forget it... These scenes of the blood will turn a huge number of people against Sisi. I'm sure of that."
Response from the international community has certainly been damning. In a statement, U.S. Secretary of State John Kerry voiced concern about the violence and said Egyptian authorities had "a moral and legal obligation to respect the right of peaceful assembly and freedom of expression."
British Foreign Secretary William Hague condemned the use of force and called on the Egyptian authorities to respect the right of peaceful protest and to "cease the use of violence against protestors, including live fire, and to hold to account those responsible."
The attacks came at a time when suspicion about the military's behavior was already rising.
On Thursday evening in Alexandria, Hakeem Abdelnaeem, who describes himself as a revolutionary socialist, suggested to me that the military might use Friday's demonstrations as an excuse to consolidate power and make a "total coup." He said he isn't sure that what happened earlier this month was a coup, but he is certain it wasn't a revolution.
Analysts also suggested that the military's recent actions might have been a play to extend its powers. "I think, it's clear that the issue is the role of the military in politics. Sisi is very much at the forefront in the process of undermining the democratic process," says Maha Azzam, an associate fellow on the Middle East and North Africa program with the Royal Institute of International Affairs.
"I think as each day passes... it's becoming less credible to stand by what is becoming clearly both a coup and a military takeover and a return of the old regime," she added. "There's no grey. You either stand with the military takeover... or you stand against the coup."
More and more Egyptians may be falling into the latter camp. The Salafist Nour Party -- a former ally of the Muslim Brotherhood which then supported the military's ouster of Morsi -- said in a statement on Wednesday that the call for protest "foreshadows civil war."