Four US Marines are presumed dead following a helicopter crash during a training mission in southern California.

The Marine Corps CH-53E Super Stallion helicopter from 3rd Marine Aircraft Wing is understood to have gone down near Plaster City at 2:35pm local time on Tuesday.

“We are currently still responding to what we have confirmed as a single helicopter incident," Naval Air Facility El Centro said in a statement on Facebook.

The identities of the crew members will be withheld until 24 hours after their next-of-kin were told of the tragedy, the military said.

The cause of the crash is being investigated.

It would be the deadliest crash for the Marines since a Navy plane went down in the Mississippi Delta in July, killing all 16 onboard.