Four crew members aboard an United States Army helicopter were killed Monday evening when the aircraft crashed at Ford Hood, in the northeastern part of the Fort Hood Range.

According to the Texas base’s press office, the UH-60 Black Hawk helicopter went down sometime after 5:49 p.m.

Soon after the crash, an “extensive search” was conducted by emergency crews, which ended when they discovered the four dead bodies of the crew members.

The victims have not yet been identified. Fort Hood has confirmed the crew was assigned to Division West, First Army.

“They were on a routine training mission at the time,” the Army base said. “… The cause of the crash is unknown at this time.”

Stay tuned to the blog for more on this developing story.

CNN