BAGHDAD, Iraq - Gunmen killed dozens of civilians Thursday and dumped their bodies in a ditch, as the government ordered a tough daytime curfew of Baghdad and three provinces to stem the sectarian violence that has left at least 114 dead since the bombing of a Shiite shrine.

Seven U.S. soldiers died in a pair of roadside bombings north of the capital, and American military units in the Baghdad area were told to halt all but essential travel to avoid getting caught up in demonstrations or roadblocks.

As the country careened to the brink of civil war, Iraqi state television announced an unusual daytime curfew, ordering people off the streets Friday in Baghdad and the nearby flashpoint provinces of Diyala, Babil and Salaheddin, where the shrine bombing took place.

Such a sweeping daytime curfew indicated the depth of fear within the government that the crisis could touch off a Sunni-Shiite civil war. “This is the first time that I have heard politicians say they are worried about the outbreak of civil war,” Kurdish elder statesman Mahmoud Othman told The Associated Press.

The biggest Sunni Arab bloc in parliament announced it was pulling out of talks on a new government until the national leadership apologizes for damage to Sunni mosques from reprisal attacks.

“It is illogical to negotiate with parties that are trying to damage the political process,” said Tariq al-Hashimi, a leader of the Iraqi Accordance Front.

Most of the bloodshed has been concentrated in the capital, its surrounding provinces and the province of Basra, 340 miles to the southeast.

Among the victims was Atwar Bahjat, a widely known Sunni correspondent for the Arab satellite television station Al-Arabiya.

Gunmen in a pickup truck shouting “We want the correspondent!” killed Bajhat along with her cameraman and engineer while they were interviewing Iraqis about Wednesday's destruction of the famed golden dome of the Shiite shrine Askariya in her hometown of Samarra.

Shiite and Sunni leaders again appealed for calm Thursday following the wave of attacks on Sunni mosques, and the number of violent incidents appeared to decline after the government extended the curfew.

Iraqi television said the curfew would extend until 4 p.m. Friday, preventing people from attending the week's most important Muslim prayer service. Officials feared mosques could be both a target for attacks and a venue for stirring sectarian feelings.

President Bush said he appreciated the appeals for calm, and called the shrine bombing “an evil act” aimed at creating strife.