HADITHA, Iraq - More than 1,000 U.S. troops on Wednesday swept into this city on the road to Syria to root out insurgents - including those loyal to terrorist mastermind Abu Musab al-Zarqawi - after rebels damaged the hospital, knocked out the electricity and prevented police from entering.

The American troops killed at least 10 suspected militants in Haditha, a Euphrates River city of 90,000 people - one of whom told the Marines that insurgents had recently killed her husband.

Speaking inside her home through a military interpreter, the woman moved her finger across her throat as she begged that her name not be used, indicating she could be killed for talking to U.S. forces. She later helped cook a breakfast of eggs and bread for the handful of Iraqi soldiers helping guard the street.

"People have always been nice to us. But you can tell the (insurgents) have been doing some damage because people are real scared," said Marine Capt. Christopher Toland, of Austin, Texas, an officer in the 3rd Battalion, 25th Regiment.

Marine Col. Stephen Davis, commander of the Haditha operation, told CNN that al-Zarqawi "clearly is an influence out here. There are clearly links to him and to his elements out here in western Iraq."

Wednesday's offensive, the second on a road to Damascus in less than a month, came as the Iraqi government demanded that Syria block insurgents from crossing the border. Iraq also asked the U.N. Security Council to renew its mandate for the 160,000 troops in the U.S.-led multinational force, saying it cannot fully defend itself alone.

The offensives are aimed at uprooting insurgents who have killed more than 620 people since a new Iraqi government was announced April 28.

The violence continued today when a car bomb exploded in Baghdad near an Iraqi police patrol, killing three policemen and two civilians and wounding 17 bystanders, officials said. Separately, gunmen fired on a group of people walking to work in Baghdad, killing four Iraqis, including a translator working for the American military, said police Lt. Hussam Noori.

Just before dawn Wednesday, U.S. Marines, sailors and soldiers encircled this city 140 miles northwest of Baghdad in troubled Anbar province.

Helicopters swept down near palm tree groves to drop off Marines who blocked off one side of Haditha, while other troops on foot and in armored vehicles established checkpoints and moved toward the city center. U.S. warplanes circled overhead.

American troops walked down city streets in neat lines, whispering instructions to each other. Except for dogs baying in the pre-dawn darkness, the city was quiet - until a large explosion shook the neighborhood.

Marines crouched with guns pointed, while others ran for cover, their ears still ringing from the explosion. One group ran through a front yard, rushing by a porch swing and a grove of trees. Sounds of battle and gunfire broke out around the city.

The Marines said six insurgents were killed in central Haditha - including one man identified as a cleric who allegedly was firing an automatic weapon. Four others were killed in separate incidents.