After days of looting and mayhem in the Iraqi capital, Americans armed newly recruited Iraqi police officers with handguns to help keep order.
Deadly gunfire broke out in the northern city of Mosul for a second straight day on Wednesday, and some of the wounded said they were shot by American troops.
Seventeen people were killed, hospital officials said, allegedly by U.S. forces. At least 18 were injured in the violence that started Tuesday in Iraq's third-largest city.
The U.S. Central Command in Qatar confirmed that American troops killed about seven Iraqis during a demonstration Tuesday but did not immediately comment on accusations that U.S. Marines shot civilians on Wednesday. Hospital administrators put the death toll at 14 Tuesday and three Wednesday.
The violence underscored that although the worst of the fighting may be over peace had not come to Iraq.
In other major developments:
Central Command spokesman Brig. Gen. Vincent Brooks said U.S. troops were trying to secure a government building in Mosul when a crowd of townspeople began throwing rocks at them, hitting them with fists, spitting at them and setting cars afire.
He said some of the Americans fired back after shots were fired at them and some members of the crowd began trying to climb over a wall into the government compound.
"Fire was, indeed, delivered from coalition forces. It was lethal fire, and some Iraqis were killed…on the order of seven," Brooks said. "The attacking was occurring from two sides and there was clear observation of men with weapons involved in firing on the building."
In Baghdad, despite the start of joint U.S.-Iraqi police patrols, throngs of looters ransacked sacks of sugar, tea, flour and other food supplies Wednesday from warehouses at the International Fairgrounds. Booty was piled into a red double decker bus, or stuffed into cars which soon became tangled in a traffic jam.
A U.S. armored personnel carrier was less than a mile away, but the soldiers did not intervene.
"The remaining areas of Baghdad that have not yet been cleared are all suspected of harboring armed regime loyalists," said Brooks.
The looting in Baghdad came a day after small numbers of Iraqi policemen resumed law enforcement duties, and made their first arrest, in an American-backed effort to curtail the looting and lawlessness that has plagued Baghdad since Saddam's regime collapsed.
In one of the U.S. military's most successful policing actions yet, a Marine patrol passing the Iraqi National Bank caught armed robbers Tuesday and recovered $3.6 million in U.S. currency.
Other Marine patrols conducted raids, sometimes accompanied by Iraqi police, to secure key infrastructure sites. U.S. forces are trying to provide security for hospitals and establish a cellphone service for emergency services to use while the regular telephone system is repaired.
In western Iraq, an U.S. Army cavalry unit accepted the surrender of the 12th Iraqi Brigade, seizing 40 tanks and close to 1,000 weapons, said Marine Maj. Stewart Upton, a U.S. Central Command spokesman. He said the number of prisoners taken had not yet been calculated.