Small arms fire brought down a US Army Black Hawk helicopter in near Karbala, Iraq, on Wednesday night.

Seven soldiers were killed and four wounded and rescued, the Pentagon said.

The US Central Command headquarters in Qatar said only six people were on the Black Hawk and that casualties could not be confirmed.

Colonel Tom Bright, the Marine Corps chief at CENTCOM's joint operations centre in Qatar, said an investigation has been launched into the incident.

Shortly afterwards, an F/A-18 Hornet fighter plane went down in southern Iraq, Central Command told BBC News Online.

Reports said a missile brought down the jet near Karbala.

The jet was based on the US aircraft carrier Kitty Hawk, ABC News reported. There was no word on the fate of the pilot.