The protests also spread to the country’s second-largest city, Alexandria, where residents said demonstrators gathered outside the main military command center and blocked several streets.
Sunday’s violence was the clearest signal yet that Egyptians are turning on the military commanders who were widely hailed as saviors eight months ago, when President Hosni Mubarak was forced from power. Many Egyptians say that swelling anger over the slow pace of reforms and the country’s economic woes could give rise to a new revolt.
“Down, down, Field Marshal Tantawi!” protesters chanted, referring to the leader of the ruling military council.
In an apparent move to discourage a new sit-in in Tahrir Square, the cabinet said late Sunday that it would impose a curfew in the area from 2 to 7 a.m.
The clashes unfolded amid growing criticism of the military leaders, who have continued to rely on loathed policies from the Mubarak era. Many Egyptians reacted with dismay to the recently announced electoral timeline, which would put off presidential elections until 2013.
“What happened today will definitely increase people’s anger toward the military and the anger of the entire Christian population,” said Wael Abbas, a well-known activist and blogger. “People’s rights are being violated, and nothing real is happening.”
Earlier Sunday, the ruling council said it would no longer try civilians in military courts, apparently bowing to pressure from activists.
Coptic Christians have been among the most vocal critics of the council. They complain that the military leadership has done too little to protect them in the wake of a string of attacks on churches this year. Coptic Christians, who make up about 10 percent of the country’s 80 million people, blame fundamentalist Muslims for the violence.
Sunday’s march began in the predominantly Christian district of Shubra, in northern Cairo, as demonstrators took to the streets to condemn the recent attack on a church in southern Egypt. The marchers were headed downtown toward the state television building, which in recent months has become a backdrop for sit-ins and demonstrations.
When they were a few blocks away, men in civilian clothes attacked the protesters with rocks, witnesses said.
Demonstrators said a harrowing and confusing scene followed. As reports of gunfire and rock-throwing spread through word of mouth and social media, thousands, including Muslims who joined the Coptic marchers, swarmed toward the state television building, where intense clashes with riot police broke out.