The political crisis in Egypt resulting from last week’s ouster of President Mohamed Morsi took a violent turn on Monday when Muslim Brotherhood supporters that had amassed near the Republican Guard’s headquarters in Cairo, where Morsi is believed to be held, were sprayed with live ammunition from the Egyptian army. Fifty demonstrators were estimated to have been killed. Hundreds more were wounded.

Morsi’s party denounced the incident as a “massacre” and urged its followers to remain in the streets to protest his removal from office.

There were conflicting eyewitness accounts of what precipitated the violence in the early morning. Officials in the Egyptian military placed the blame solely on the Muslim Brotherhood protesters who turned violent, citing the death of two policemen and one soldier from gunfire that came from the crowd. The protesters “came at us with machine guns, with live rounds, with birdshot,” said an Egyptian army spokesman who added that Morsi’s supporters “tried to break into” the installation, forcing security to defend themselves.

Protesters described the event differently. Britain’s The Guardian newspaper cited one Islamist claiming that army units around the building started shooting indiscriminately into the crowd in order to push them from the area. “The army units that were standing in front of the Republican Guard headquarters first started shooting teargas,” he said, “then live ammunition above people’s heads.”

Whoever started the violence, the event in downtown Cairo had a devastating effect on Egypt’s interim government, led by the former chief justice Adli Mansour. The Salafist al-Nour party, the only Islamist group that supported the army’s takeover, pulled out of talks in protest while the president of the al-Azhar University, Ahmed el-Tayeb, who also backed the coup, warned of a civil war if the situation didn’t calm down.

In a sign of how serious the situation had become, the United States embassy in Cairo closed for business on Friday and urged American citizens in the country to exercise maximum safety. Calls on Egypt’s leaders to refrain from violence continued to pour out of the White House, as well as statements urging the military and interim government to include all Egyptian parties in the transition process.

The overthrow of Mohamed Morsi by the armed forces was jubilantly supported by millions of Egyptians — a welcome development for the army’s top brass who lost a considerable amount of support during their sixteen months in power after the previous president, Hosni Mubarak, was ousted in early 2011. Monday’s shooting showed, however, that the newfound honeymoon for Egypt’s generals could quickly dissipate if the nation continues to go down its current path — one of violence between opposing ideological camps, a depressed economy and political instability.