Few details of Wednesday's incident were immediately available, but some Iraqis blamed U.S. troops. The shooting appeared to have taken place at an open-air market about 300 to 400 yards from the governor-general's office.
Tensions have been high in Mosul, a city of 700,000 people where Arabs and Kurds are highly suspicious of each other. Many of the area's Arabs also have a strong affinity for nearby Syria, which has drawn intense criticism in recent days from Washington.
At the U.S. Central Command in Qatar, Brig. Gen. Vincent Brooks said Tuesday's bloodshed occurred as American special operations soldiers and Marines were trying to secure a government building for use as a meeting center.
He said that when a group of Marines arrived at the walled compound, people threw rocks at the troops, punched and elbowed them, and spat at them. He said an Iraqi ambulance with loudspeakers arrived later and began urging on the crowd, which turned over a car and set it on fire.
Brooks said the U.S. troops guarding the wall fired warning shots after seeing some people in the crowd shooting weapons into the air. The Americans then were shot at and began firing at some people in the crowd, including some who tried to climb over the wall, he said.
"It was lethal fire, and some Iraqis were killed as a result of that," Brooks said. "We think the number is somewhere on the order of seven, and there may have been some wounded as well."
Earlier reports quoted witnesses as saying as many as 10 Iraqis may have died and dozens were wounded. Those accounts said the crowd became unruly during a speech by the city's new governor-general outside his office.
Several of those wounded in Wednesday's incident accused American troops of firing at them from rooftops, but a Marine sergeant near the scene denied that. He said U.S. troops on top of a building came under fire from gunmen on another building across a park and the Americans shot back.
Mohammed Rabih Sheet, an administrator at Jumhuriya Hospital, said three people were killed and 11 wounded, including two children.
Six of the wounded who spoke to a reporter said Americans shot them.
Mozafar Ahmad, a 14-year-old who suffered wounds in one arm and above one knee, said he was hit while on a bus passing the governor's office.
"I saw Americans standing on the street and on the roof shooting. Seven others in the bus were also injured," he said. "I didn't notice how many Americans there were.
Amal Mahmoud, a 40-year-old taxi driver, said he saw U.S. troops shoot at people.
"There were people inside the central bank, which is next door to the governor's office. They had been looting money for several days. Police were standing outside the bank and fired shots in the air to disperse the looters. The Americans started firing at the people in front of the governor's office," rather than at the looters, he said.
U.S. Central Command has said throughout the war that it goes to extreme lengths to avoid civilian casualties. No reliable estimates of civilian dead and wounded exist, although Iraqi claims at least 1,200 have died and 4,000 have been wounded.
Central Command or CENTCOM has launched investigations into several incidents of alleged civilian casualties resulting from American attacks on Iraq.
Some of the incidents have been alleged by the Iraqi government, which has obvious motives for making false claims.
CENTCOM has already investigated and refuted claims that a U.S. missile killed 14 people in a Baghdad market on March 26.
Other incidents being probed include other attacks on Baghdad markets killing over 60 people, alleged cluster bombing in Hillah, attacks on two buses, a shooting at a checkpoint that killed seven civilians and the killing of three journalists in Baghdad last week.
Even when civilian deaths have been the direct result of a U.S. combat operation, CENTCOM and the Pentagon have insisted throughout the campaign that any noncombatant casualties were Iraq's fault.
They placed the blame on Iraqi military's tactics — like using human shields, irregular forces out of uniform, and at least one suicide bomber — and its strategy of locating military facilities near civilian areas.