FORT CARSON, Colo. (AP) — The military has released the names of two Colorado-based soldiers who were killed in a helicopter crash in California.

The Army said Monday 1st Lt. Clayton R. Cullen and Chief Warrant Officer 2 Kevin F. Burke died Saturday when an AH64 Apache helicopter crashed during training at the National Training Center at Fort Irwin, California.

Cullen was from Indiana and Burke from California. The Army didn't release their hometowns.

The cause of the crash is under investigation.

Cullen and Burke were assigned to the 4th Combat Aviation Brigade of the 4th Infantry Division at Fort Carson, Colorado.