A U.S. Marine Corps helicopter crashed near El Centro, Calif., on Tuesday afternoon during a routine training mission, and the military says all four aboard are presumed dead.

"Four crew members were aboard" the CH-53E Super Stallion helicopter, the 3rd Marine Aircraft Wing said in a statement. "The status of all four is presumed dead pending positive identification."

The helicopter went down about 2:35 p.m. local time, the statement said. El Centro is about 100 miles east of San Diego.

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The cause of the crash is being investigated, the statement said.

Earlier, Reach Air Medical quickly dispatched two helicopters to the crash site, a spokesperson, Donnie Wharton, told The Desert Review.

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