U.S. troops smashed down workshop doors and junkyard gates with sledgehammers, crowbars, explosives and even armored vehicles in a massive raid to hunt for pro-Saddam Hussein (search) militants and stamp out the increasingly bold anti-U.S. resistance.

In downtown Samarra (search), soldiers blasted open the front gates of walled homes, bringing cries of women and children inside. At least a dozen men suspected of waging guerrilla attacks were rounded up -- though others got away, apparently tipped off about the raid.

"Locksmiths will make a lot of money these days," said a U.S. soldier, laughing as he sat atop a Bradley fighting vehicle in the city's industrial zone, where doors were shattered.

Nearly 2,500 troops from the 4th Infantry Division launched Operation Ivy Blizzard (search) before dawn in the city of of 200,000, about 20 miles south of the town where Saddam was captured Saturday. Samarra, north of Baghdad, has emerged as a hotspot in anti-U.S. guerrilla action.

A day earlier, U.S. soldiers snared a suspected rebel leader and 78 other people, all in one building near Samarra where they apparently were planning attacks. On Monday, guerrillas in the city ambushed an American patrol, sparking a battle in which soldiers killed 11 attackers.

"Samarra has been a little bit of a thorn in our side," said Col. Nate Sassaman. "It hasn't come along as quickly as other cities in the rebuilding of Iraq. This operation is designed to bring them up to speed."

"No one knows the town better than we do, we're gonna clean this place. They've made a mistake to attack U.S. forces. We will dominate Samarra," he said.

With Saddam in custody, the most wanted Iraqi fugitive is Izzat Ibrahim al-Douri, a high-ranking member of the former regime thought to be organizing anti-U.S. attacks. But it was unclear whether U.S. officials think al-Douri is in the Samarra area.

A core of about 1,500 fighters is thought to be in Samarra, said Sassaman's deputy, Capt. Matthew Cunningham. In Wednesday's sweep, soldiers used satellite global positioning devices to locate buildings pre-marked as targets.

As Apache helicopters flew overhead, troops downtown fanned out in squads of 14 to storm several walled residencial compounds, using plastic explosives to break in. In one compound, the blast at the gate shattered windows in the house itself, and a one-year-old baby was cut by glass. U.S. medics treated the injury while other soldiers handcuffed four men, who were later released.

The loud blasts mixed with the sound of women and children screaming inside the houses. At one point, there was a short exchange of gunfire, but it was not immediately clear what happened.

At another home, an explosion ignited a small fire.

Elsewhere, a suspect was punched in the head and a soldier said: "You're dead. You're dead."

Troops later moved on to the industrial area, where they found little One military official said he suspected insurgents moved much of their equipment to farms outside town.

Lt. Jack Saville said suspects had been tipped off about the raid, either by Iraqis working on the U.S. base in Tikrit or by Samarra residents who saw the U.S. military vehicles massing in the region in recent days.

Sassaman said troops in Samarra seized four rocket-propelled grenade launchers and a dozen assault rifles, as well as bomb-making material.