Two American military personnel were killed in separate attacks in Iraq Friday, military officials said, as a homicide bomber detonated explosives outside a town hall, killing two people but causing no injuries to U.S. troops.

The homicide bomber struck at 11 a.m. in Riyadh (search), about 16 miles west of Kirkuk (search), said police Col. Sarhat Qadir. Some American soldiers were inside the town hall at the time of the explosion, but they were unhurt.

Hundreds of Iraqis have been killed by homicide bombers who have targeted Iraqi government buildings, police stations, headquarters of political parties and religious gatherings since the U.S.-led war on Iraq began.

A roadside bomb killed an American soldier from the U.S. Army's 1st Armored Division and wounded another in Baghdad (search) Friday, the military said. And Thursday, a U.S. Marine was killed "as a result of enemy action" in Anbar province, according to a statement from Camp Fallujah, the Marine base in the area.

Also on Friday, a cleric in Fallujah condemned the mutilation of four slain American contractors in the city, but did not criticize the killings.

U.S. Marines are responsible for security in Fallujah, the site of Wednesday's ambush of the four contract workers, but the military did not say whether the Marine was killed in the city.

U.S. officials promised punishment for the culprits of Wednesday's attacks "at the time and place of our choosing."

About 600 worshippers gathered at the Hmood al-Mahmood Mosque in Fallujah, just a few blocks from the site of the ambush, to hear Sheik Fawzi Nameq's sermon.

"Islam does not condone the mutilation of the bodies of the dead," Nameq said.

"Why do you want to bring destruction to our city? Why do you want to bring humiliation to the faithful? My brothers, wisdom is required here," said Nameq, who refrained from making a judgment on the killings.

Clerics in Fallujah strongly oppose the U.S.-led occupation and often use sermons to criticize American authority.

The charred remains of the four Americans were dragged through the streets for hours after insurgents ambushed their vehicles. Two of the corpses were hung from a bridge as people beat them with shoes and a pole. Iraqi police eventually collected their remains at the request of American troops.

Senior Fallujah cleric Sheik Khalid Ahmed had said that Muslim preachers in mosques across the city would tell their followers in Friday sermons that the mutilation of the bodies was wrong. He did not say whether they would condemn the killings.

"Prophet Muhammad prohibited even the mutilation of a dead, mad dog and he considered such a thing as religiously forbidden. What happened in Fallujah is a distortion of Islamic principles and it is forbidden in Islam," he said.

The U.S.-appointed Iraqi Governing Council on Thursday condemned "the cold-blooded slaughter and mutilation of civilians" and vowed that "those murderers who carried out these terrorist acts will not hinder or disrupt the march of our people toward the dawn of freedom and democracy."

Brig. Gen. Mark Kimmitt, deputy chief of U.S. military operations in Iraq, pledged to hunt down those who carried out the killings, but said clashes could be avoided if Fallujah city officials arrest those responsible.

"If they were to deliver these people to the criminal justice system, we will come back in and start the rebuilding of Fallujah. That is their choice," he said.

A Fallujah city council member, who spoke on condition of anonymity, said the council issued a statement Thursday "condemning the mutilation of the bodies because it contradicts the teachings of Islam," but he did not say whether a decision was made to take action against those responsible for the killings.

Police manned regular roadside checkpoints Friday, and there was no sign of U.S. troops in or around the city, where a mood of defiance remained despite the possibility of U.S. military retaliation.

However, those living on the outskirts reported some families had left their homes for the safety of relatives' dwellings deep inside the city. Traffic was heavy and shops were open.

"Islam bans what was done to the bodies, but the Americans are as brutal as the youths who burned and mutilated the bodies," said Mahdi Ahmed Saleh, a 61-year-old retired primary school principal who runs a grocery store.

Mohammed Mikhlef, a 45-year-old contractor, added: "We just do not know what the Americans will do now. But, by God, they are capable of so much cruelty."

U.S. commanders defended their decision not to send forces into Fallujah to retrieve the bodies, which were picked later by Iraqi police.

Kimmitt said U.S. forces didn't respond for fear of ambushes and the possibility that insurgents would use civilians as human shields. "A pre-emptive attack into the city could have taken a bad situation and made it even worse," he said.

"We are not going to do a pell-mell rush into the city. It will be deliberate, it will be precise and it will be overwhelming," he said. "We will re-establish control of that city. ... It will be at the time and place of our choosing."

Fallujah, 35 miles west of Baghdad, has seen some of the worst anti-U.S. violence since the beginning of the occupation. The insurgents appear to enjoy the support — or at least acquiescence — of a significant part of the population.

Late Thursday, gunmen fired on two police cars in the city of Baqouba, 30 miles northeast of Baghdad, killing three officers and wounding two, according to Loua'ie Adel, a hospital official said.

The Associated Press contributed to this report.