Two US Marine helicopters carrying 12 crew members collided off the Hawaiian island of Oahu during a nighttime training mission, and rescuers were searching a debris field in choppy waters Friday, military officials said.
There was no immediate word on what caused the crash or if any survivors had been found.
The transport helicopters each had a crew of six from Marine Corps Base Hawaii and crashed just before midnight Thursday, officials said. The CH-53Es came from the 1st Marine Aircraft Wing, Marine Capt. Timothy Irish said.
A Coast Guard helicopter and C-130 airplane spotted a debris field offshore early Friday.
The search includes aircraft from the Navy and Air Force, a Honolulu Fire Department rescue boat and Coast Guard cutters, officials said.
A swell approaching the area will bring dangerously high waves to beaches and seas of up to 20 feet (6 meters) near the rescue operation, National Weather Service meteorologist Matthew Foster said. Winds will be relatively calm.