Three New York National Guard members were killed Wednesday night when their UH-60 medical evacuation helicopter crashed in a farmer’s field in Mendon, New York during a routine training flight.

The crew and aircraft were assigned to C Company of the 1st Battalion, 171st General Support Aviation Battalion, according to the New York National Guard. The three crew members were not immediately identified, pending notification of next of kin.

The circumstances of the crash are under investigation and will involve the Federal Aviation Administration. According to the Monroe County Sheriff’s Office, 911 calls reported that the National Guard helicopter was flying very low and there was engine sputtering before it crashed at 18:32.

The helicopter was already fully engulfed in flames by the time that several local fire departments, state police, and representatives of the U.S. military responded to the crash, the sheriff’s office said. Debris was spread over an area of several city blocks, and authorities closed the road near the crash site.