The BBC and CNN just broke this story.
Blackwater security personnel on board a helicopter in Baghdad (2005)
As many as 20,000 private security contractors are working in Iraq
Iraq has cancelled the licence of the private security firm, Blackwater USA, after it was involved in a gunfight in which at least eight civilians died.
The Iraqi interior ministry said the contractor, based in North Carolina, was now banned from operating in Iraq.
The Blackwater workers, who were contracted by the US state department, apparently opened fire after coming under attack in Baghdad on Sunday.
Thousands of private security guards are employed in lawless Iraq.
They are often heavily armed, but critics say some are not properly trained and are not accountable except to their employers.
"We have revoked Blackwater's license to operate in Iraq. As of now they are not allowed to operate anywhere in the Republic of Iraq," Interior Ministry spokesman Brig. Gen. Abdul Kareem Khalaf said Monday. "The investigation is ongoing, and all those responsible for Sunday's killing will be referred to Iraqi justice."