There are conflicting reports on what happened here. Fox News says they have eyewitnesses who suggest it was a peaceful protest, a sit-in, and that the Egyptian Army just started shooting:
FOX NEWS – At least 40 people were killed Monday in clashes outside a military building in Cairo where supporters of the former president were holding a sit-in, an Egyptian health ministry official said.
Ministry spokesman Khaled el-Khatib said initial reports also indicated at least 322 were wounded, although he gave no details on the circumstances of the killings.
Eyewitnesses tell Fox News that Muslim Brotherhood supporters were fired upon with birdshot and rounds from automatic weapons at around 5:30 a.m. local time, during morning prayers. Fox News sources who were at the scene shortly after the shooting described seeing Muslim Brotherhood supporters with large chest wounds and fatal gunshot wounds in their backs.
The Muslim Brotherhood have blamed the attacks on the Egyptian military who were standing guard over the demonstration near to the Raba El Adwyia mosque.
But the military says that a Brotherhood terrorist group tried to storm the Republican Guard building and that it left 6 of their officers with serious injuries and one dead:
Military spokesman Col. Ahmed Mohammed Ali said initial information indicates that gunmen affiliated with the Brotherhood tried to storm the Republican Guard building shortly after dawn, firing live ammunition and throwing firebombs from a nearby mosque and rooftops. One police officer on the scene was killed, he said. Another military spokesman, who declined to be named because he was not authorized to brief reporters, said five from the Brotherhood side were killed.
A statement by the armed forces published on the state news agency said “an armed terrorist group” tried to storm the Republican Guard building, killing one officer and seriously injuring six. The statement said the forces arrested 200 attackers, armed with guns and ammunition.
My gut tells me that the Army is telling the truth. After all, it was their mission to keep the country from descending into chaos and massacring peaceful protesters would undermine everything they’ve worked for. Also, considering the penchant for Islamists to die for their cause and the inability for reporters to discern a Muslim Brotherhood ‘eyewitness’ from an actual eyewitness, it wouldn’t surprise me if the goal of this terrorist group was to incite a civil war by storming the compound in a rescue attempt for Mohammed Morsi knowing many of them would die.
After the incident the anti-Morsi Salafist Al Nour party left the interim government condemning the clashes as a ‘massacre‘:
Nour Party head Younis Makhyoun said on his Facebook page on Monday that, in response to the “Republican Guards House massacre,” his party has decided to completely withdraw from the political scene and from partaking in putting in place a roadmap announced by Sisi.
Makhyoun added that the party has also decided to stop collaborating with President Adly Mansour. He said that the party will issue a statement to clarify its position in the next few hours.
Nader Bakkar, the party’s assistant head of media affairs, said that the group has decided to withdraw from all negotiations in a preliminary response to the alleged massacre.
On Twitter, Bakkar added that the party will not remain silent about the “Republican Guards House massacre.”
“We wanted to stop bloodshed, but rivers of blood are being spilled,” he said.
Turkey has also dismissed the Army’s claims and are condemning it as ‘massacre’ as well:
Turkish Foreign Minister Ahmet Davutoglu condemned the Cairo shooting in which at least 42 people died Monday, describing the incident as a “massacre.” …
“I strongly condemn the massacre that took place in Egypt at morning prayer in the name of the fundamental human values which we have been advocating,” Davutoglu said on Twitter.
The Turkish foreign minister called for the start of a political normalization process that respects the national will of the Egyptian people.
The Turkish government shares Islamist roots with Morsy’s Muslim Brotherhood.
No matter what exactly happened, this is exactly the kind of incident that will only fortify the pro-Morsi supporters and could lead to a civil war in Egypt. If that was indeed the goal of the Muslim Brotherhood, I’m guessing they may have accomplished it.