CAIRO — Security forces clashed with supporters of Egypt’s ousted president early Saturday, killing at least 65 protesters, the Health Ministry said, in the country’s bloodiest incidence of violence since the military deposed Mohammed Morsi.

In chaotic scenes, pools of blood stained the floor and bodies were lined up under white sheets in a makeshift hospital near the site of the battles in eastern Cairo as doctors struggled to cope with the flood of dozens of wounded.

The extent of the carnage underlined the willingness of police to unleash deadly firepower against any expansion of Islamist-led protests demanding the reinstatement of Morsi.

Military-backed authorities are feeling emboldened after millions turned out for nationwide rallies Friday called by the army chief in support of a tough hand against what he called “terrorism.”

Interim Vice President Mohamed ElBaradei, a longtime pro-democracy campaigner who backed the military’s ouster of Morsi, raised one of the few notes of criticism of the bloodshed in the new military-backed leadership.

“I highly condemn the excessive use of force and the fall of victims,” he wrote in a tweet, though he did not directly place blame for the use of force. He added that he is “working very hard and in all directions to end this confrontation in a peaceful manner.”

The bloodshed also pointed to the Islamists’ readiness to challenge the security forces as Morsi’s supporters try to win over public support for their cause.

The fighting, which began before dawn and stretched out over several hours, was the deadliest bouts of violence since the military ousted Morsi on July 3 in the wake of massive protests demanding his removal. Soon after Morsi’s fall, more than 50 of his supporters were killed in a similar outbreak of violence outside a headquarters of the Republican Guard.

A leading figure of Morsi’s Muslim Brotherhood, Mohammed el-Beltagy, blamed the violence on army chief Gen. Abdel-Fattah el-Sissi’s call for rallies on Friday.

“This is the mandate el-Sissi took last night – to commit massacres and bloodshed against peaceful protesters denouncing the military coup,” el-Beltagy said in a statement on his Facebook page.

The clashes began after a crowd of Morsi supporters late Friday moved out of their main sit-in camp where they have been located for nearly three weeks, in front of the Rabaah al-Adawiyah Mosque.