U.S. Marine Corps officials are investigating after two pilots died in a helicopter crash during a training mission in southwestern Arizona.

A statement from the Marine Corps Air Station says the crash of the AH-1Z Viper occurred at about 8:45 p.m. Saturday.

A spokesman for the station says the crash occurred on the vast Marine Corps Air Station Yuma training grounds.

Capt. Gabriel Adibe says no additional information is immediately available.

The names of the pilots who were killed have not been released pending notification of their families.

The station is located about 2 miles (3.2 kilometers) from Yuma and the 1,300 square mile (3,367 square kilometer) training ground is one of the world’s largest military installations.

(AP)