BAGHDAD, Iraq - Two car bombs exploded in the insurgent stronghold of Ramadi today, killing four Iraqis and prompting clashes between U.S. troops and gunmen. In the northern city of Mosul, another vehicle bomb went off, wounding four Americans.

Also in Mosul, three decapitated bodies - two Iraqis and an unidentified corpse - have been found in and around the city, a coroner said, the latest in a grisly campaign of beheadings by militants who have been snatching foreigners and Iraqis accused of helping the United States.

U.S. warplanes pounded the vast Baghdad slum of Sadr City overnight after an American patrol came under gunfire, the military said today. Hospital officials said at least one Iraqi was killed in the violence in the district, a stronghold for Shiite militiamen.

Near Baghdad, one soldier from the U.S. Army's 13th Corps Support Command was killed Monday night and two were injured when their convoy hit a homemade bomb, the military said. As of Monday, 1,058 members of the U.S. military have died since the start of the war in March 2003, according to the Pentagon.

Ramadi, 70 miles west of Baghdad, is one of the Sunni Triangle cities where U.S. and Iraqi commanders are considering launching a new push to clear out insurgents ahead of key January elections.

Intensifying violence - including near-daily car bombs and persistent abductions - and the insurgents' dominance in several cities have raised concerns over the vote. Iraqi and U.S. leaders insist they will be held on schedule, though some officials have said voting may not be possible in the most violence-torn areas, which are largely Sunni Muslim.

A powerful group of Sunni Muslim clerics today warned against leaving out parts of the country, saying it would undermine the vote and be tantamount to fragmenting Iraq.

In Ramadi today, a booby-trapped car exploded near the city's Grand Mosque as a U.S. military convoy passed. Four Iraqis inside a car near the explosion were killed and two bystanders were wounded, said Dr. Dia'a al-Haity, a doctor at Ramadi General Hospital.

Witnesses said a wounded U.S. soldier was seen being carried away by his colleagues after the blast, which punched a crater into the ground and mangled a nearby vehicle. The U.S. military said it had no informatin on the incident.

Earlier today, another car bomb exploded in another part of the city, sparking a gunbattle between U.S. forces and gunmen. Al-Haiti said two Iraqis were killed and four wounded in the fighting.

Ramadi is frequently the scene of clashes. On Monday, U.S. Marines spotted militants planting a roadside bomb and in the ensuing gunbattle two insurgents were killed and a third wounded, said Marine spokesman 1st Lt. Lyle Gilbert.

A car bomb in the city today targeted a U.S. convoy, wounding four American soldiers, the U.S. military said.

U.S. troops opened fire after the explosion, killing three Iraqis in a passing vehicle and wounding a number of others, said police 2nd Lt. Mohammed Ahmed.

Mohamed Qadir Youssef, a worker at the al-Jomhuria Hospital, said three people were killed and three others wounded.

Meanwhile, coroner Riyadh Mohammed of al-Jomhuria Hospital said three beheaded bodies have been found in and around the city in the past two days. Two were Iraqis, while the third was unidentified, he said.

Besides the bodies found in Mosul, the headless body of a police officer was discovered in the Kirkuk area north of Baghdad. Another headless corpse of a man was found of south of Baghdad with authorities initially saying he appeared to be of Western origin.

Meanwhile, U.S. Marines have distributed $367,300 in condolence and damage repair payments in the holy city of Najaf since three weeks of fighting ended there in August, the military said.

The statement did not specify how many families have benefited from the payments.

U.S. and Iraqi troops fought for three weeks with followers of renegade Shiite cleric Muqtada al-Sadr in Najaf, 100 miles south of Baghdad. The clashes ended with a peace deal brokered by Iraq's top Shiite cleric Grand Ayatollah Ali al-Husseini al-Sistani.

"We are working hard to demonstrate goodwill to the people of Najaf who incurred losses during fighting in August," said Col. Anthony Haslam, commander of the 11th Marine Expeditionary Unit.

Condolence payments are made to express sympathy to those who were injured or lost relatives in the fighting. Collateral damage payments are intended for those who suffered damage to their homes, businesses or other property.

While Najaf has calmed since the uprising, U.S. troops and al-Sadr militiamen have fought almost daily in Baghdad's Sadr City district, home to more than 2 million people.

Hospital officials in Sadr City said today that at least one person was killed in skirmishes overnight. Residents said they continued to hear loud explosions until dawn.

U.S. soldiers were fired on late Monday during a patrol in Sadr City, said Capt. Brian O'Malley, spokesman for the U.S. 1st Cavalry Division. They returned fire as U.S. AC-130 planes targeted insurgent machine gun crews on the ground, he said.

Abu Tar al-Kinani, the spokesman for the insurgents in Sadr City, said the overnight attack was a "liquidation operation" and an effort to keep al-Sadr's movement from taking part in elections.

On Monday, the former head of the U.S. occupation in Iraq, L. Paul Bremer, said the United States did not have enough troops in Iraq after ousting Saddam Hussein and "paid a big price" for it.

Bremer said he arrived in Iraq on May 6, 2003, to find "horrid" looting and a very unstable situation.

"We paid a big price for not stopping it because it established an atmosphere of lawlessness," Bremer told an insurance group in White Sulphur Springs, W.Va. The group released a summary of his remarks in Washington.

"We never had enough troops on the ground," Bremer said. But he insisted he was "more convinced than ever that regime change was the right thing to do."

Rumsfeld said Monday he does not expect a civil war to erupt in Iraq, and pointed to the recent retaking of the former insurgent stronghold of Samarra as evidence of progress in stabilizing the country.

"I don't think it's going to happen," Rumsfeld said in New York at the Council on Foreign Relations, when asked about the threat of civil war. "But what has to be done in that country is what basically was done in Samarra over the last 48 hours."