The U.S. military confirmed that an Army helicopter went down south of Baghdad on Thursday, wounding four U.S. personnel.

"There were 9 personnel on board including passengers and crew. Four personnel were injured and have been evacuated," the military said in a statement.

The statement did not say what caused the helicopter crash, but said the incident is under investigation.

Earlier, a witness said that gunmen opened heavy machine-gun fire on a U.S. helicopter while flew over a rural area outside the town of Latifiyah, some 35 km south of Baghdad.

"There was a U.S. helicopter in the sky then I heard heavy machine-gun fire and the helicopter went down in a rural area outside the town," Ali Salih said.

U.S. troops rushed to the area and cordoned the scene, he added.

The Sunni stronghold town of Latifiyah is part of the area dubbed the Triangle of Death in which insurgents frequently attacked the U.S. and Iraqi forces.

The latest incident brings the number of U.S. aircraft crashed in Iraq to nine in this year.

Source: Xinhua