Baghdad, Iraq ? Scores of terrified Iraqis fled a besieged town Sunday, waving white flags and hauling their belongings to escape a second day of fighting between U.S. Marines and al-Qaida-led militants along the Syrian border. U.S. and Iraqi troops battled insurgents house-to-house, the U.S. military said.

The U.S. commander of the joint force, Col. Stephen W. Davis, told The Associated Press late Sunday that his troops had moved “about halfway” through Husaybah, a market town along the Euphrates River about 200 miles northwest of Baghdad.

At least 36 insurgents have been killed since the assault began Saturday and about 200 men have been detained, Davis said. He did not give a breakdown of nationalities of the detainees. Many were expected to be from a pro-insurgent Iraqi tribe.

Davis would not comment on U.S. and Iraqi government casualties but said the militants were putting up a tough fight because “this area is near and dear to the the insurgents, particularly the foreign fighters.”

“This has been the first stop for foreign fighters, and this is strategic ground for them,” he said by telephone.

Earlier Sunday, Brig. Gen. Donald Alston, a U.S. military spokesman, told reporters in Baghdad that none of the 3,500 U.S. and Iraqi troops had been killed so far.

The U.S. Marines said American jets struck at least 10 targets around the town Sunday and that the U.S.-Iraqi force was “clearing the city, house by house,” taking fire from insurgents holed up in homes, mosques and schools.

Residents of the area said by satellite phone that sounds of explosions diminished somewhat Sunday, although bursts of automatic weapons fire could be heard throughout the day. The residents said coalition forces warned people by loudspeakers to leave on foot because troops would fire on vehicles.

Marine Sergeant Dennis Howard talks with local children at the displaced persons compound Sunday in Husaybah, Iraq, during Operation Steel Curtain.

“I left everything behind – my car, my house,” said Ahmed Mukhlef, 35, a teacher who fled Husaybah early Sunday with his wife and two children while carrying a white bed sheet tied to a stick. “I don’t care if my house is bombed or looted, as long as I have my kids and wife safe with me.”

The Marines said in a statement that about 450 people had taken refuge in a vacant housing area in Husaybah under the control of Iraqi forces. Others were believed to have fled to relatives in nearby towns and villages in the predominantly Sunni Arab area of Anbar province.

U.S. officials have described Husaybah, which used to have a population of about 30,000, as a stronghold of al-Qaida in Iraq, led by Jordanian extremist Abu Musab al-Zarqawi. Husaybah had long been identified as an entry point for foreign fighters, weapons and ammunition entering from Syria. From Husaybah the fighters head down the Euphrates valley to Baghdad and other cities.

Several people identified as key al-Qaida in Iraq officials have been killed in recent airstrikes in the Husaybah area, the U.S. military has said. Most were described as “facilitators” who helped smuggle would-be suicide bombers from Syria.

Damascus has denied helping militants sneak into Iraq, and witnesses said Syrian border guards had stepped up surveillance on their side of the border since the assault on Husaybah began.

The Americans hope the Husaybah operation, codenamed “Operation Steel Curtain,” will help restore enough security in the area so the Sunni Arab population can participate in Dec. 15 national parliamentary elections.

In Baghdad, Mohsen Abdul-Hamid, head of the largest Sunni Arab political party, sharply criticized “all military operations directed against civilian targets” because they “lead to the killing of innocent people and the destruction of towns and cities.”

Saleh al-Mutlaq, head of another Sunni faction and a member of the committee that drafted the new constitution, accused the Americans and their Iraqi allies of mounting “a destructive and killing operation of secure cities and villages” on the “pretext that they hide and secure terrorists.”

The U.S.-led assault includes about 1,000 Iraqi soldiers and will serve as a major test of the fledgling army’s capability to battle insurgents – seen as essential to enabling Washington to draw down its 157,000-strong military presence.