BAGHDAD — The U.S. military in Baghdad said today it was investigating what appeared to be the crash of a civilian aircraft after reports a helicopter was shot down over a volatile Sunni area in the capital.

The military said it had no evidence any U.S. forces aircraft were involved but was investigating "what appears to be a crashed civilian aircraft."

Most aircraft used in Iraq belong to the coalition forces, but at least one private security company flies helicopters.

A U.S. official said there was no indication any U.S. Embassy staff or diplomats were on the aircraft.