Four Camp Pendleton Marines were killed when their helicopter crashed during a routine training flight late Wednesday afternoon near the Salton Sea, a Marine spokesman said.
The UH-1 "Huey" utility helicopter crashed at about 5 p.m. in farmland outside Calipatria, about 125 miles east of San Diego, killing all on board, the spokesman said Wednesday night.
The aircraft was assigned to the Marine Light Attack Helicopter Squadron 169, based at Camp Pendleton north of San Diego, he said.
Names of the dead were being withheld until their families could be notified, he said.
It was the second fatal crash involving a Camp Pendleton helicopter within the past four months.
Two Marine aviators, one a squadron commander, were killed June 19 when their Cobra attack helicopter crashed at the Naval Weapons Station near Fallbrook during a nighttime training mission.
The cause of the crash has yet to be determined.
Before the June accident, the last fatal accident by a Camp Pendleton-based helicopter occurred July 27, 1990, when two Marines were killed and three others injured after their UH-1N Huey crashed in the Chocolate Mountains of Imperial County during a training mission.