US forces fanned out across Iraq on Sunday to seize arms and put down potential foes in a campaign called Operation Desert Scorpion, a day after a deadline passed for Iraqis to hand in heavy weapons. Some Iraqi residents said the raid was conducted too harshly.

Hundreds of troops supported by helicopters and tanks swooped on Fallujah and several other Iraqi towns in the dead of night. They handcuffed and forced men to lie face down on floors and rousted women from their beds while searching for illegal arms, in a swift and coordinated action that residents of the raided homes complained was heavy handed.

After a three-hour operation in Fallujah, eight suspected leaders of the anti-American resistance were taken into custody.

The nationwide campaign "is a combat operation to defeat the remaining pockets of resistance," said Capt. John Morgan, a spokesman for the Army's V Corps.

By the midnight Saturday close of a two-week nationwide amnesty for surrendering banned arms, only a fraction of the thousands of heavy weapons, anti-tank rockets and anti-aircraft missiles had been turned in.

Three hours after the deadline, 1,300 troops of the 3rd Infantry Division's 2nd Brigade conducted the first raids, cordoning off Fallujah, a town of 200,000 about 35 miles west of Baghdad.

Acting on intelligence tips, they swept through 16 buildings at four locations, said Col. David Perkins, the brigade commanding officer. Troops found bombs, bomb-making materials and illegal communications equipment.

No American or Iraqi casualties were reported.

Perkins said the operation was designed to limit inconvenience to residents. After daybreak, convoys of trucks bearing food, medicines, school supplies and toys rolled into town, items requested by local leaders in meetings with brigade commanders.

Nevertheless, Iraqis complained of insensitive behavior by US troops during the raids, asserting that some arrested people had no involvement in attacks on American troops.

"We got rid of one problem and now we have a bigger one," said Jassim Mohammed, turning his face away to wipe away tears. US troops raiding his home arrested two of his sons, Salah, 25, and Mohammed, 26. "Even Saddam never did this to us."

Insurgents have fired on US soldiers in the Fallujah area almost daily since they entered Iraq's Sunni Muslim heartland on April 24. US troops there have killed at least 24 Iraqis and wounded 78, while the insurgents have killed four US soldiers and wounded 21.

Residents and local leaders claim the attackers are troublemakers who don't come from the area. Pentagon officials have said foreign volunteers also are still active in Iraq, including Syrians, Saudis and Yemenis.

Last week, a coordinated air and ground strike killed about 70 insurgents, most of them foreigners, at a tent camp near the Syrian border. On Thursday, 74 suspected al-Qaida sympathizers were arrested near the northern city of Kirkuk, the military said. Morgan, the V Corps spokesman, said the men were "being detained and questioned" but would not give further details.

The raids Sunday morning had been widely anticipated. On Saturday, warnings of the impending attack were broadcast from Fallujah's mosques. When the raids began, some residents flashed porch lights or sounded sirens to warn that US troops were approaching.

Staging small, random attacks and provoking a brutal response by the authorities has been a typical way of starting an insurgency. US commanders have struggled to develop a strategy that allows them to deal with anti-American forces while building goodwill with civilians at the same time.

The mood was festive at one clinic, as pharmacists stocked shelves and doctors distributed free medications. "We are all very happy about the delivery, it will help us a great deal," Dr. Jassim Ibrahim Naja said.

Other residents had a lukewarm response.

"No one asked them for food," said Mohammed Mattar Saleh, a teacher and father of 10 who said he hasn't been paid his salary in months. "What we need is our back pay."

Capt. Anthony Butler, of the 3rd Infantry Division, voiced frustration at the failure to win over the population. "We spend 29 days fighting a war, killing anyone who had a weapon or resisted. Then we spent two months in Baghdad trying to transition from killing anything we saw to being nice."

While pursuing illegal weapons stockpiles, the United States increased its radio appeals for Iraqis involved in weapons of mass destruction programs to surrender for trial, offering leniency for those who cooperate.

"It's time to leave your hideouts," said an announcer on an AM radio station in Baghdad operated by US Army's Psychological Operations personnel. "If you come voluntarily and give information about weapons of mass destruction and their launch vehicles, the United States will do its best to give you a just trial in accordance with the law."

Nearly three months of searching have turned up no Iraqi weapons of mass destruction, whose alleged existence was the main justification for going to war.