TWENTYNINE PALMS, Calif. -- The military says two Marines were killed when their helicopter crashed during a training exercise in Southern California.

The Third Marine Aircraft Wing chopper was carrying just the two when it went down late Friday afternoon at the base in Twentynine Palms.

Both Marines on board died as a result of crash injuries.

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The Marine Corps says it's withholding their names for 24 hours to notify relatives.

Wing commander Maj. Gen. Michael Rocco says in a statement released by Marine Corps Air Station Miramar: "Our hearts go out to the families and friends of the two Marines we lost in this tragic accident."

There was no immediate word on a cause of the crash, which is under investigation.

No other details were available early Saturday.