BAGHDAD -- Last Feb. 7, a sniper employed by Blackwater USA, the private security company, opened fire from the roof of the Iraqi Justice Ministry. The bullet tore through the head of a 23-year-old guard for the state-funded Iraqi Media Network, who was standing on a balcony across an open traffic circle. Another guard rushed to his colleague's side and was fatally shot in the neck. A third guard was found dead more than an hour later on the same balcony.

Eight people who responded to the shootings -- including media network and Justice Ministry guards and an Iraqi army commander -- and five network officials in the compound said none of the slain guards had fired on the Justice Ministry, where a U.S. diplomat was in a meeting. An Iraqi police report described the shootings as "an act of terrorism" and said Blackwater "caused the incident." The media network concluded that the guards were killed "without any provocation."

The U.S. government reached a different conclusion. Based on information from the Blackwater guards, who said they were fired upon, the State Department determined that the security team's actions "fell within approved rules governing the use of force," according to an official from the department's Bureau of Diplomatic Security. Neither U.S. Embassy officials nor Blackwater representatives interviewed witnesses or returned to the network, less than a quarter-mile from Baghdad's Green Zone, to investigate.

The incident shows how American officials responsible for overseeing the security company conducted only a cursory investigation when Blackwater guards opened fire. The shooting occurred more than seven months before the Sept. 16 incident in which Blackwater guards killed 17 civilians at another Baghdad traffic circle.

The Feb. 7 shootings convulsed the Iraqi Media Network, one of the prominent symbols of the new Iraq, in anger and recrimination.

U.S. officials and the security company, now known as Blackwater Worldwide, offered no compensation or apology to the victims' families, according to relatives of the guards and officials of the network, whose programming reaches 22 million Iraqis.

"It's really surprising that Blackwater is still out there killing people," Mohammed Jasim, the Iraqi Media Network's deputy director, said in an interview. "This company came to Iraq and was supposed to provide security. They didn't learn from their mistakes. They continued and continued. They continued killing."

A Blackwater spokeswoman, Anne E. Tyrrell, said the company's guards came under "precision small-arms fire" and fired back with "well-aimed shots." The company was unable to comment further because of operational security and contractual obligations, she said. "This was absolutely a provoked incident," Tyrrell said.

U.S. officials were "overwhelmingly convinced" that the Blackwater guards acted appropriately, based on information they had provided, according to the diplomatic security official. He spoke on condition of anonymity because a joint U.S.-Iraqi commission is investigating private security matters, including previous Blackwater shootings. Shortly after the Feb. 7 incident, the official said, the U.S. Embassy briefed an Iraqi government official and invited him to discuss the matter further, but the embassy never heard from him again.

Under State Department rules for the use of force, security contractors are authorized to use deadly force only if there is no safe alternative and the guards or the people they are protecting face "imminent and grave danger." The Blackwater guards said they came under fire from the building and responded, the security official said.

"The embassy conducted a review of the circumstances surrounding the whole shooting incident and essentially what happened is, after going over all the reports, interviewing all the personnel that were involved in it, talking with people that were coming back in the motorcade, they concluded that the actions of the security team fell within the approved rules," the official said.

"To say Blackwater was the only source of information for this investigation is completely false," the security official added. U.S. officials declined to say who else was contacted as part of the probe or to provide any details about the assertions of Blackwater guards that they came under fire.