U.S. and Iraqi security forces scoured Fallujah for remaining insurgent fighters and pounded the city's southernmost neighborhoods with heavy artillery and bombs late Sunday night, as military commanders declared victory seven days after launching their largest operation since the U.S.-led invasion of Iraq in March 2003.

"The city has been seized," said Lt. Gen. John F. Sattler, commander of the 1st Marine Expeditionary Force. "We have liberated the city of Fallujah."

Marines found the mutilated body of a Western woman in a street Sunday as they searched for the remaining fighters, the Associated Press reported. The disemboweled body, which could not be immediately identified, was wrapped in a blood-soaked blanket, the Marines said.

Two Western women abducted last month from Baghdad are known to be missing. Margaret Hassan, 59, director of CARE International in Iraq, and Teresa Borcz Khalifa, 54, a Polish-born longtime resident of Iraq, were taken at gunpoint.

The military said 38 U.S. troops had been killed and 275 wounded since the offensive operation began Nov. 8. Three of the fatalities resulted from noncombat injuries. Six Iraqi soldiers have been killed and more than 40 wounded. Military commanders estimated that between 1,000 and 1,200 insurgents have been killed.

Marine units engaged fighters throughout the day, poking at what Sattler called "isolated pockets of enemy resisters."

"If they are trapped and isolated and want to fight till the death, we'll have no choice but to accommodate them," he said.

With Iraqi soldiers following closely behind, the Marines went door-to-door Sunday, searching for fighters and stockpiles of weapons. A day earlier, advancing Army units found evidence of a highly trained and well-organized fighting force dressed in professional military uniforms.

"The enemy is broken into very small groups," Sattler said during a visit with wounded troops at a Naval field hospital outside the city, about 35 miles west of Baghdad. "They don't have eyes. They can't see outside. They are truly broken into isolated pockets."

A U.S. official in Baghdad said most of the fighters carried no identification.

"The normal Iraqi would carry minimal identification, ID cards at least. Food ration cards or something," the official said, speaking on the condition of anonymity. "These people are carrying nothing."

U.S. and Iraqi forces have detained more than 1,000 military-age men since the battle started, and Sattler said he expected that two-thirds would be questioned and freed.

U.S. forces failed to capture Abu Musab Zarqawi, the Jordanian leader of a group linked to al Qaeda that has claimed responsibility for numerous car bombings targeting Iraqi civilians and security forces, assassinations of local leaders and beheadings of foreign hostages.

"I feel we really had an impact" on Zarqawi's network, Sattler said. "We don't know where he is. Maybe he's dead and we don't know. We weren't really focused on him."

Iraqi soldiers who participated in the battle said Sunday that they also felt confident that the insurgency had been broken.

"They cannot move," said a 22-year-old soldier from the Sadr City neighborhood of Baghdad who gave his name only as Ahmed. He had been shot in his left shoulder and was recovering at an Iraqi army base outside the city.

"We destroyed the head of the snake, their leaders," he said. "They don't have anyone to lead them."

Although Iraqi forces fought mainly in the rear of advancing U.S. troops, they were responsible for keeping areas clear after the Americans pushed through, a role that military commanders said would remain vitally important after the combat operation had ended.

Sattler said U.S. forces would keep a "hand on the shoulder" of the Iraqi security forces.

A U.S. official in Baghdad said the Fallujah battle was nearly over. "There are some groups still fighting but it's pretty much the end of the game. It is clearly not a battle that is going to go on for days and day and days."

Correspondent Karl Vick in Baghdad and special correspondent Omar Fekeiki contributed to this report.

U.S. Marines in western Fallujah pass a mutilated body that officials said may be that of a Western woman, possibly one of two abducted last month. U.S. and Iraqi forces searched the city for remaining small groups of insurgents.U.S. Marines take up positions near the bridge in Fallujah where the bodies of two American contractors, killed by insurgents, were strung up in March. A Marine, above, puts his mark on one of the bridge's beams. An American official in Baghdad said the Fallujah battle was nearly over.