BAGHDAD, Oct. 4 -- U.S. military reports from the scene of the Sept. 16 shooting incident involving the security firm Blackwater USA indicate that its guards opened fire without provocation and used excessive force against Iraqi civilians, according to a senior U.S. military official.

The reports came to light as an Interior Ministry official and five eyewitnesses described a second deadly shooting minutes after the incident in Nisoor Square. The same Blackwater security guards, after driving about 150 yards away from the square, fired into a crush of cars, killing one person and injuring two, the Iraqi official said.

The U.S. military reports appear to corroborate the Iraqi government's contention that Blackwater was at fault in the shooting incident in Nisoor Square, in which hospital records say at least 14 people were killed and 18 were wounded.

"It was obviously excessive, it was obviously wrong," said the U.S. military official, who spoke on condition of anonymity because the incident remains the subject of several investigations. "The civilians that were fired upon, they didn't have any weapons to fire back at them. And none of the IP or any of the local security forces fired back at them," he added, using a military abbreviation for the Iraqi police. The Blackwater guards appeared to have fired grenade launchers in addition to machine guns, the official said.

The company has said its guards acted appropriately after being attacked. Blackwater Chairman Erik Prince, in previously unpublicized remarks prepared for delivery at a congressional hearing Tuesday, said the Blackwater guards "came under small-arms fire" and "returned fire at threatening targets."

State Department spokesman Sean McCormack hinted Thursday that Blackwater guards could face legal proceedings. Announcing a decision to have FBI agents lead a State Department inquiry into the shootings, he said it was "a hedge against the possibility that an investigation leads to the point where there may need to be a referral" to U.S. prosecutors.

In response to the shootings, the Pentagon is also conducting a broad review of its relationship with the private security contractors it employs. The military has issued about 7,000 weapons permits to private contractors, the senior U.S. military official said, but has stopped issuing new permits until it can review who has the weapons and how they have been used.

Many U.S. military officials are critical of Blackwater because its guards have a reputation for reckless behavior that officials say reflects poorly on American troops in Iraq. Iraqi citizens often do not distinguish between U.S. soldiers in Humvees and Blackwater guards in armored vehicles.

"They tend to overreact to a lot of things. They maneuver around town very aggressively, they've got weapons pointed at people, they cut people off, of course their speeds -- I mean a whole bunch of things they do fairly consistently. But when it comes to shooting and firing, they tend to shoot quicker than others," the U.S. military official said.

U.S. soldiers have reviewed statements from eyewitnesses and video footage recorded at Nisoor Square, the official said. Members of a U.S. unit working with Iraqi police were present in the area at the time of the shootings. U.S. soldiers also helped ferry victims to hospitals.

Blackwater, whose primary task in Iraq is to protect U.S. diplomats, has been unwilling to share information about the incident with the U.S. military, the official said, adding that military officials went to Blackwater's compound in the Green Zone but were denied access to company managers.

Anne Tyrell, a Blackwater spokeswoman, said the company was "cooperating with all investigations" and deferred further comment until they are complete.