Two soldiers were killed Saturday when their AH-64 Apache helicopter crashed during a routine training mission at the National Training Center at Fort Irwin, California.

“The cause is currently under investigation and next of kin notifications ongoing, therefore we can provide no further details at this time,” Army spokesman Lt. Col. Jason Brown said in a statement to Army Times.

A separate official who spoke to Fox News said the helicopter was with the 4th Infantry Division of Fort Carson, Colorado. It was at Fort Irwin as part of a regular training rotation, the official told Fox News.

This is a developing story. We will update it as more information is available.