Six US military personnel were killed when a KC-135 aerial refueling plane crashed in western Iraq on Thursday. Authorities are investigating the cause of the crash and have ruled out both hostile and friendly fire.

The victims were aged 28 to 38. Three were from the 6th Air Refueling Wing at MacDill Air Force Base in Florida, and three were from the 121st Wing at Rickenbacker in Ohio.

The crash occurred during a period of heightened US military presence in the region due to tensions with Iran.