The US military in Iraq has launched a formal investigation into a video that appears to show security contractors firing randomly at Iraqi civilians.
Troops and security staff often fire warning shots at vehicles
The video appeared on a website reportedly run by a former employee of London-based Aegis Defence Services.
The company, one of the largest private security contractors in Iraq, has launched its own investigation.
The video, shot from the back of a vehicle, shows cars coming under fire as Elvis Presley music plays.
One car swerves off the road and crashes after being hit by bullets.
Gunshots can be heard on the clips, but those doing the shooting are not visible.
Rules of engagement
US military spokesman Lt Col Barry Johnson said the military's Criminal Investigation Division has launched an inquiry.
An Aegis spokeswoman, Sara Pearson, said Aegis and the US military began a joint investigation two weeks ago into whether Aegis employees were involved and, if so, whether the shooting fell outside the company's rules of engagement.
She said the results of the investigation could be released next week.
Troops and security contractors commonly fire warning shots to scare off vehicles that get too close, for fear of suicide bombers, the AP news agency says.
Aegis Defence Services Ltd won a $293m (£169m) contract from the US government last year to provide a range of services in Iraq.
Its remit includes the protection of civilians and soldiers travelling in Iraq.
The company says its rules of engagement "allow for a structured escalation of force to include opening fire on civilian vehicles under certain circumstances".