All four crew members in a U.S. Marine Corps helicopter are presumed dead after it crashed during a training flight in southern California, an official said.
The crash occurred on Tuesday afternoon at 2:35 pm (2135 GMT) near El Centro, according to the 3rd Marine Aircraft Wing, a unit of the U.S. Marine Corps stationed in Miramar north of San Diego.
The cause of the crash is still being investigated and the identity of the crew members is being withheld for 24 hours until their family are notified.
The helicopter involved was a Sikorsky CH-53E Super Stallion.
The 3rd Marine Aircraft Wing is the largest unit of the U.S. Marine Corps on the West Coast.
The crash would be the deadliest for the Marines since a July crash in the Mississippi Delta, which killed all 16 aboard.
Earlier Tuesday, a Marine Corps Harrier jet crashed in the East African nation of Djibouti. According to U.S. Naval Forces Central Command based in Bahrain, the pilot ejected shortly after takeoff and was in stable condition.