Men in civilian clothes attacked a largely Islamist group of protesters camped outside the ministry at dawn. The protest was started by Islamists several days ago over the disqualification from the presidential race of Hazem Salah Abu Ismail, an ultraconservative, and had been joined by other groups in a broader demonstration against the ruling military.
Nine died from gunshot wounds, many to the head, and two others were reported to have been stabbed to death. A number of leading candidates for the presidency, including Abdel Moneim Aboul Fotouh, who split from the Muslim Brotherhood last year, and Mohammed Morsi, who is standing for the Brotherhood-backed Freedom and Justice party, announced they were suspending their campaign activities, three weeks before the first round of voting.
Clashes continued throughout Wednesday morning between protesters and the unidentified assailants, who threw petrol bombs and fired live ammunition, birdshot and teargas, according to witnesses.
"There is a deluge of blood on the street which extends for many metres. One injured man had his back sliced by the thugs," said Abdelrahman Hany, a rights advocate at the Arabic Network for Human Rights Information, who was present when the attacks began.
Hany said he believed the attackers were linked to the state security apparatus. "How else would they possess teargas to fire at us?" he asked.
The deaths add to the already febrile air surrounding the elections, after veiled threats attributed to the ruling Supreme Council of the Armed Forces to postpone the voting, and accusations from different sides of efforts to undermine the transfer to civilian rule.
Many of the protesters are supporters of Abu Ismail, who was thrown out of the presidential race because his mother held dual Egyptian-US citizenship, which violates electoral rules. The sit-in also included members of secular movements such as the unaffiliated Revolutionaries Without Direction, an umbrella group that aims to remove 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 demonstration near the ministry on Friday. "Next Friday is the end for military rule," he said.
Morsi said he was halting his campaign for two days "in opposition to the killing and the bloodshed", and warned the military government against using the violence as an excuse to postpone the vote.
Ashraf Thabet, deputy parliamentary speaker of the Salafist al-Nour party, which is backing the candidacy of Fotouh, cautioned against jumping to any quick conclusions over who was responsible for the killings. "We need to find out what really happened and hope that this crisis passes so that the elections can take place as planned," he said.
Egypt has seen sporadic bouts of violence since the fall of Hosni Mubarak, and there are growing doubts over whether the ruling army council intends to surrender power fully.
The military council said it might hand over power after the first round of votes, on 24 May, if there is an outright winner. The suggestion came from Ahmed al-Fadali, head of the Democratic Peace party, who met the generals on Wednesday. The Muslim Brotherhood boycotted the meeting.
