Waving white flags, Iraqis fled the city of Samarra on river boats today as US forces claimed victory in the first step of an offensive aimed at taking control of rebel-held cities.
But the operation in Samarra brought condemnation from residents about the cost in lives and suffering, and militants in Fallujah are expected to put up a tougher fight.
In a statement, the US military said warplanes had conducted "another precision strike" in Fallujah today, the latest in a campaign of strikes targeted at Jordanian militant Abu Musab al-Zarqawi and his followers.
In Samarra, aid organisations said they were concerned about a lack of water and power and the fate of hundreds of families forced to flee. One man who said he escaped the city today said a number of civilians had been killed.
Around 3,000 US troops and 2,000 Iraqi soldiers stormed Samarra on Friday.
"This has been a successful operation ... We're very confident that the future of Samarra is good," Major-General John Batiste, the commander of the US 1st Infantry Division, which led the assault on Samarra, told CNN.
"It is over in Samarra," Iraqi Defence Minister Hazem Shaalan told Al Arabiyatelevision.
In 36 hours of fighting in the city, the US military said it killed 125 militants and seized 88.
Residents said bodies were left in the streets, untended due to the fear of snipers.
Families tried to bury their dead today, but the road to the cemetery was blocked off by US troops, witnesses said.
Some people unable to flee the city by road travelled on small boats along a river holding up white flags as helicopters hovered overhead.
The Iraqi Red Crescent Society, the Muslim equivalent of the Red Cross, said it was trying to deliver food, water and first aid to needy civilians, and said it feared for the fate of at least 500 families forced to flee to areas north of Samarra.
Iraq's interior minister, who visited Samarra on Saturday, said no civilians had been killed in the day-and-a-half blitz, a statement that angered some residents who said they had lost family members, including children, in the fighting.
The US military said it had tried to keep civilian casualties to a minimum but said there was always a cost.