CAIRO -- Soldiers fired on a Cairo mosque on Saturday where supporters of the ousted president, Mohamed Morsi, were sheltering, briefly turning a central thoroughfare into a war zone in a further sign that Egypt's new military rulers are struggling to impose order days after security forces killed hundreds of antigovernment Islamists.
Soldiers and policemen eventually stormed and cleared the Fath mosque, according to the state news agency. By day's end, though, it was unclear if there were any casualties at the site, and as curfew fell, it also remained unclear how many Islamists were arrested.
The standoff began on Friday when Mr. Morsi's supporters turned the mosque into a field hospital and a morgue during deadly clashes with the security services. It appeared that the security forces this time had worked to try to negotiate an end to the standoff.
But the task of ending the siege was complicated by hundreds of civilian opponents of the Islamists who surrounded the mosque and beat Mr. Morsi's supporters as they emerged, despite attempts by the soldiers to safely bring out the Islamists. The civilians, armed with rubber hoses, metal pipes or wooden clubs, also attacked or detained journalists in the area.
It was not clear whether the vigilantes surrounding the mosque on Saturday were actively collaborating with the security services, who have long relied on plainclothes enforcers to brutally break up demonstrations. Some echoed the relentless campaign by government officials and the state news media to paint Mr. Morsi's supporters as terrorists.
Civilians have added a layer of menace to Egypt's violence in recent days, as so-called popular committees set up checkpoints in neighborhoods, searching cars and occasionally robbing their drivers. On Friday, armed men roamed Cairo freely, their allegiances, to Mr. Morsi or to the military, unclear.
Standing among the police officers on Saturday, a man tried to stir up a crowd. "The mosque is full of weapons," he said, though a reporter who visited the mosque late Friday saw no weapons inside.
Several reporters were attacked by civilians outside the mosque on Saturday, including a reporter for The Guardian, Patrick Kingsley, who wrote on Twitter that he was surrounded by a mob that "duffed me up a bit," and that his laptop and cellphone were stolen before he was taken to a police station.
On Saturday, an adviser to Egypt's interim president, Mustafa Hegazy, lashed out at the foreign news media and Western countries for ignoring violence by the Islamists, while warning "those who give international cover or financial cover" to terrorists.
"Egypt is not a soft state," he said. "It is not a follower. It has never been and will never be."
The violence at the mosque came a day after battles throughout Egypt -- between security forces and Islamists, and civilians fighting among themselves -- left at least 173 people dead, according to an official count.
The standoff at the mosque was emblematic of Egypt's wider chaos, with no end in sight to a feud between Mr. Morsi's supporters and the military that has devolved into violent conflict since security services killed hundreds of people at the sit-ins last week.
There were signs on Saturday that the civil strife could intensify, as the government proposed new measures aimed at further limiting the influence of the main Islamist movement, the Muslim Brotherhood, or possibly trying to eradicate it.
And, perhaps adding further energy to the cycle of bloodshed and revenge, the Brotherhood announced that the son of its spiritual leader, Mohamed Badie, had been killed during the fighting outside the mosque on Friday "by live ammunition." The movement had previously announced that the grandson of its founder, Hassan al-Banna, was killed during the same clashes.
Last week, the 17-year old daughter of a senior Brotherhood leader was killed when the army and the police tore through the encampment of Mr. Morsi's supporters at the Rabaa al-Adawiya mosque.
The interim prime minister, Hazem el-Beblawi, submitted a proposal to the ministry that regulates nongovernmental groups to ban the Islamist movement, his spokesman said Saturday. In a news conference, the spokesman, Sherif Shawky, said the world had seen the "organized terrorism and sinful aggressions on the citizens" by a "small faction that lost its mind and was blinded by the lust for power, and the dreams of coming back."
It was unclear if Mr. Beblawi was suggesting that the Brotherhood could be allowed to maintain its political arm, the Freedom and Justice Party. Mr. Shawky asserted that the government was still interested in an "inclusive" political process, but only after "this homeland belongs to everyone," he added.
In the meantime, the government has continued to sideline its opponents. The state news media said that hundreds of Brotherhood members had been arrested across Egypt over the last two days, including some it said had firearms or explosives.
The military and the police surrounded the Cairo mosque after the bloody confrontation with Mr. Morsi's supporters on Friday. So did the hundreds of pro-government civilians, whom the authorities made no large scale attempts to disperse. Early Saturday, witnesses said the military was attempting to negotiate with the Islamists to abandon the mosque, perhaps fearing they would start another sit-in in the middle of the city, which the government has said it will prevent.
There was sporadic gunfire throughout the day in front of the mosque and in the surrounding area, near Ramses Square, as soldiers fired weapons in the air to disperse the civilians as the army tried to extricate the Islamists.
It turned into a barrage on Saturday afternoon, as soldiers and policemen focused their fire on the mosque minaret. State news media later said they were responding to a gunman had been shooting from the minaret, and that the authorities had arrested at least one more Brotherhood leader.
This article originally appeared in The New York Times.