4 feared dead after Marine helicopter crash in California The helicopter crashed during a training mission in southern California.

Four crew members are presumed dead after a Marine helicopter crashed on Tuesday during a training mission in Southern California, the military said.

Officials said the CH-53E Super Stallion crashed around 2:35 p.m. Tuesday near El Centro, not far from the U.S.-Mexico border. The helicopter belonged to the 3rd Marine Aircraft Wing in San Diego.

The Marine Corps said it would withhold the identities of the deceased for 24 hours until next-of-kin notifications were complete.

"Four crew members were aboard the aircraft. The status of all four is presumed dead pending positive identification," the Marines said in a statement.

The Naval Air Facility in El Centro sent its condolences to those impacted by the tragedy early Wednesday in a Facebook post.

"Our thoughts and prayers go out to the families and friends affected by the tragedy earlier today," the post said.

"We want to thank our friends and neighbors in the Imperial Valley for all of their support and prayers today," it added in separate post.

The cause of the crash is under investigation.

It would be the deadliest crash for the Marines since a KC130T transport plane went down in July near the Mississippi Delta, killing all 16 aboard, according to an Associated Press report.