KEY POINTS
  • The helicopter was with the 3rd Marine Aircraft Wing out of the Miramar air station in San Diego, according to a base press statement.
  • The cause of the crash is under investigation.
A U.S. CH-53E Super Stallion helicopter.

A Marine helicopter crashed during a Southern California training mission and all four crew members were believed killed, the military said.

The CH-53E Super Stallion went down shortly after 2:30 p.m. Tuesday near El Centro, a few miles from the U.S.-Mexico border.