CAIRO - Egypt's prosecutor general on Tuesday began investigating 650 people suspected of involvement in violence that killed dozens in front of a military compound in Cairo a day earlier, the state news agency said.
At least 55 people were killed on Monday when soldiers opened fire on a crowd protesting last week's military overthrow of President Mohamed Morsi.
Morsi's Muslim Brotherhood and survivors said they were conducting peaceful dawn prayers when security forces, unprovoked, began to fire on them.
The military says armed men attacked troops in the area around the Republican Guard compound, and that one officer was killed in the clashes and 42 were wounded.
Egypt's state news agency MENA said suspects were accused of crimes including murder, attempted murder, "thuggery," carrying firearms and ammunition without licenses, obtaining explosives, compromising public security for "terrorist purposes" and blocking roads.
The report did not say who exactly was under investigation, but referred to the incident as "an attack by armed terrorist groups on soldiers and officers of the armed forces."
Egypt's interim administration said on Monday it had formed a judicial committee to investigate the killings, which deepened political turmoil that has gripped Egypt since a 2011 uprising overthrew Hosni Mubarak.