A small plane has crashed at Camp Pendleton, leaving two men seriously injured and another with moderate injuries.

Marine Corps spokesman Lt. Riley Whaling says the crash occurred shortly before 6 p.m. Saturday near a freeway off-ramp. Witnesses told officials that the plane appeared to develop engine trouble before the crash.

The Cessna 172 was flying from John Wayne Airport in Orange County to Montgomery Field in San Diego.

All three people aboard were taken to hospitals. Their conditions were not immediately available.

The cause of the crash is under investigation.