Investigators said in a report now under review by the Justice Department as many as five of the company's guards opened fire during the shootings, and as many as 14 of the deaths were unnecessary, the New York Times reported Wednesday.

"I wouldn't call it a massacre, but to say it was unwarranted is an understatement," one official who asked not to be identified told the Times.

The company said its guards opened fire when they perceived a security threat to their four-car convoy, and denied any wrongdoing.

A separate U.S. military review of the shootings concluded all of the killings were unjustified and potentially criminal, the Times said, although prosecutors have yet to decide whether to seek indictments.

Rep. David Price, D-N.C., sponsored legislation to extend U.S. criminal law to contractors serving overseas, and said he hopes new Attorney General Michael Mukasey would make the issue "a top priority."