Security contractors opened fire in western Baghdad on Sunday, killing at least nine civilians and wounding 18, Iraqi police said. The U.S. Embassy said contractors working for the State Department were involved in an incident but provided no further details, according to AP. The shootings happened about 12:30 on Nisoor Square in the predominantly Sunni neighborhood of Mansour, a police officer said, speaking on condition of anonymity because he wasn't authorized to release the information. The security contractors were in a convoy of six SUVs and left the scene after the shooting. The policeman said he did not have more details, but a witness said the shooting erupted after an explosion. The U.S. Embassy said State Department contractors were involved in an incident in Baghdad but released no details saying an investigation was under way. American soldiers arrived at the scene after the shootings occurred and were not involved, military spokesman Lt. Col. Scott Bleichwehl said. «We saw a convoy of SUVs passing in the street nearby. One minute later, we heard the sound of bomb explosion followed by gunfire that lasted for 20 minutes between gunmen and the convoy people who were foreigners and dressed civilian clothes. Everybody in the street started to flee immediately,» said Hussein Abdul-Abbas, who owns a mobile phone store in the area. There are tens of thousands of private security contractors, including many Americans and Britons, operating in Iraq to offer protection for Westerners and dignitaries as the country has plummeted toward anarchy and civil war. They are equipped with automatic weapons, body armor, helicopters and bulletproof vehicles and operate with little or no supervision, accountable only to the firms employing them.