Assailants attacked Egyptian protesters gathered outside the Defense Ministry in Cairo to call for an end to military rule, killing at least five people and wounding 50 on Wednesday, security officials said.

The violence is the latest episode in more than a year of turmoil in Egypt following the ouster of longtime authoritarian ruler Hosni Mubarak and will likely fuel more tensions just three weeks ahead of presidential elections. The military generals who took over from Mubarak in February last year have promised to hand over power to a civilian administration by July 1.

The security officials said the dawn attack was carried out by unidentified assailants who set upon several hundred protesters who had camped out in the area since early Saturday to press their demand for an end to military rule.

Many of the protesters are supporters of Hazem Salah Abu Ismail, an ultraconservative Islamist who was thrown out of the presidential race because his mother held dual Egyptian-U.S.­ citizenship, which violates eligibility rules to run in the election.

The officials said the assailants used rocks, clubs and firebombs. They spoke on condition of anonymity because they were not authorized to speak to the media.

Unidentified assailants have consistently attacked protesters around the Defense Ministry, with troops and police deployed in the area not attempting to intervene.

In past attacks, Egypt's pro-military state media said the assailants were residents angered by the disruption caused by the protests to life in their neighborhood. But pro-democracy activists maintain the assailants operate with the blessing of the police or the military, and that they may even be on their payroll.

Wednesday's attack came hours after the protesters outside the Defense Ministry said they had caught an off-duty army officer who came to the area to look around, an act that must have been taken by the generals as an insult to the armed forces.