Many of the protesters are supporters of Hazem Abu Ismail, an ultraconservative Islamist who was thrown out of the presidential race because his mother held dual Egyptian-U.S. citizenship, which violates electoral rules.
The sit-in also included members of secular movements such as the unaffiliated Revolutionaries Without Direction, an umbrella group hoping to gather disparate forces with the aim of removing the military junta that has ruled Egypt during the transitional period.
A member of that group, Mohamed Dahaby, accused the Interior Ministry of hiring the attackers at the behest of the military and said the group was planning a major demonstration near the ministry on Friday. "Next Friday is the end for military rule," he said.
Liberal pro-democracy groups, which were also involved in the protests demanding the army return immediately to the barracks, condemned the attack at the Defense Ministry.
The 6 April youth movement decried the "massacres" and demanded that the army be held to account for its "crimes committed against the revolution and revolutionaries".
"These practices are a continuation of the cleansing and killing methods which the army council uses to suppress the revolution," the group said in a statement.
Intellpuke: You can read this article by Guardian Correspondent Abdel-Rahman Hussein, reporting form Cairo, Egypt, in context here: www.guardian.co.uk/world/2012/may/02/egyptian-protesters-killed-cairo