The Pentagon has released the identities of six US crew members killed during the crash of a refuelling aircraft in western Iraq earlier this week, which authorities said was not caused by “hostile fire,” AFP reports.

The Pentagon said the six members killed in the crash were: John Klinner, 33, of Auburn, Alabama; Ariana Savino, 31, of Covington, Washington; Ashley Pruitt, 34, of Bardstown, Kentucky; Seth Koval, 38, of Mooresville, Indiana; Curtis Angst, 30, of Wilmington, Ohio; and Tyler Simmons, 28, of Columbus, Ohio.

The first three were members of the US Air Force, while the latter three were stationed with the US Air National Guard.

The crash remains under investigation, Pentagon officials said, but US Central Command previously stated that “the loss of the aircraft was not due to hostile fire or friendly fire.”