Saif Shamari made his usual morning run on Wednesday to buy goods at a warehouse on Sinak Street, a commercial strip that is normally bustling with shop owners hauling crates of merchandise. But when he arrived, Shamari found the warehouse doors shuttered and the street deserted.

Like Sinak Street, much of Baghdad was subdued on Wednesday after militia fighters loyal to Moqtada Sadr, a militant Shiite Muslim cleric, warned that they would carry out attacks throughout the capital.

Those attacks had not come by dusk, and there were few reports of roving bands of Sadr's Mahdi Army fighters. But it was clear that seven days of fighting between U.S.-led forces and the Mahdi Army in southern Iraq and in Baghdad's Sadr City neighborhood have frightened a city already unnerved by months of violence.

"All we want is to make our country stable," said Shamari, a slight 23-year-old. "I think the only solution is to make the coalition forces leave Iraq. Today is like a day off. . . . There are no police in the street."

The standoff with Sadr comes as Iraq's interim government is grappling with a violent insurgency that many Iraqis had hoped would disappear once the U.S.-led occupation relinquished political authority June 28. Gunmen on Wednesday killed a regional head of the Supreme Council for the Islamic Revolution in Iraq, one of Iraq's largest Shiite political parties. The official, Ali Khalisi, was killed in a drive-by shooting in Mahmudiyah, 15 miles south of Baghdad.

Meanwhile, an Islamic Web site posted video footage that appeared to show militants in Iraq beheading a dazed man identified as a CIA agent. The authenticity of the video could not be verified. A U.S. official, speaking on condition of anonymity, said the CIA had accounted for all its employees, the Associated Press reported.

More than 80 foreigners and several Iraqis have been kidnapped in Iraq in recent months by insurgents demanding that their countries pull out troops or private workers.

In Anbar province west of Baghdad, two U.S. Marines were killed when a CH-53 helicopter crashed Wednesday night. Three people aboard were injured and evacuated to a military medical facility. The cause of the crash was under investigation, a Marine statement said.

On Wednesday, Baghdad seemed to be holding its collective breath as residents waited for possible repercussions of the fighting in the Shiite holy city of Najaf, 90 miles south of Baghdad, where Marines and Army troops continued to battle Sadr's forces near the gold-domed Imam Ali shrine.

Shop owners in the capital opened late and closed early. In areas usually jammed with customers, restaurants were half full. Many of those who did venture out were stockpiling food to last for up to four days, a practice usually reserved for when the country is on the verge of war.

"People just feel it's not the right time to go out," said Jawad Katham, 26, who sells cold drinks from a stall in the Zayouna district. "I used to stay here until midnight. Last night, I quit at 9."

For the most part, fighting in Baghdad has been contained to Sadr City, the large Shiite slum in the northeast part of the capital where nearly 40 percent of the city's populace lives. Residents, spurred by reports of fighting near holy sites in Najaf, have taken up arms on recent nights and threatened to fight alongside the militants if necessary.

"We will never stop," pledged Mohammad Qasim, 21, of Sadr City. "We want to kick the Americans out of the country."

Fighting early Monday and Tuesday night in Baghdad killed eight people and wounded 69, according to the Iraqi Health Ministry. In the cities of Kut, Meisan, Basra and Diwaniyah, 22 people were reported killed and 150 others wounded.

Sadr issued a statement through Ahmed Shaibani, a spokesman in Najaf, calling on members of his militia to "continue defending your country and holy sites even if you see me captured or killed." Shaibani said that even if U.S. forces defeat the militia in Najaf, "the resistance will still exist in other parts of Iraq."

Moderate Shiites have condemned Sadr and his militia for the latest violence, though some said they understood the frustration behind the fighting.

"There is no electricity, no water and many people who do not have jobs," said Alaa Dabagh, 49, a store owner in Baghdad's Karrada district. "I wish to God Sadr never did this. But maybe in my mind I can see that Sadr is trying to force the Iraqi government to do something for the people."

Many in Zayouna, a wealthy neighborhood favored by officials in toppled president Saddam Hussein's government, had little good to say about Sadr's followers.

"Allawi went to Najaf to offer peace," said Rafa Abdel Rahman, 43, referring to a visit by Prime Minister Ayad Allawi on Sunday. "But these people are hopeless. They are hoodlums and street people. Saddam knew how to deal with them: with force."

Special correspondent Luma Mousawi contributed to this report.

Iraqis loyal to Shiite cleric Moqtada Sadr pray in Najaf, where U.S. military commanders delayed what was expected to be a decisive battle. Story, Page A18.Mahdi Army fighters roam the streets in Baghdad's Sadr City, where residents have threatened to fight alongside the militants.