BAGHDAD — The Iraqi government said today that it was pulling the license of an American security firm allegedly involved in the fatal shooting of civilians during an attack on a U.S. State Department motorcade in Baghdad.

The Interior Ministry said it would prosecute any foreign contractors found to have used excessive force in the Sunday shooting. It was latest accusation against the U.S.-contracted firms that operate with little or no supervision and are widely disliked by Iraqis who resent their speeding motorcades and forceful behavior.

Interior Ministry spokesman Abdul-Karim Khalaf said eight civilians were killed and 13 were wounded when security contractors believed to be working for Blackwater USA opened fire in a predominantly Sunni neighborhood of western Baghdad.

"We have canceled the license of Blackwater and prevented them from working all over Iraqi territory. We will also refer those involved to Iraqi judicial authorities," Khalaf said.

The spokesman said witness reports pointed to Blackwater involvement but said the shooting was still under investigation. It was not yet clear if the measure against Blackwater was intended to be temporary or permanent.

Blackwater, based in Moyock, N.C., provides security for many U.S. civilian operations in the country.

Phone messages left early this morning at the company's office in North Carolina and with a spokeswoman were not returned.

The U.S. Embassy said a State Department motorcade came under small-arms fire that disabled one of the vehicles, which had to be towed from the scene near Nisoor Square in the Mansour district.

An embassy official provided no information about Iraqi casualties but said no State Department personnel were wounded or killed. He spoke on condition of anonymity because he was not authorized to speak to media.

He said the shooting was being investigated by the State Department's diplomatic security service and law enforcement officials working with the Iraqi government and the U.S. military.

Prime Minister Nouri al-Maliki late Sunday condemned the shooting by a "foreign security company" and called it a "crime."

The decision to pull the license was likely to face a challenge as it would be a major blow to a company that was at the forefront of one of the main turning points in the war.

Today's action against Blackwater was likely to give the unpopular government a boost, given the contractors' widespread unpopularity.