Two Marine CH-53 helicopters collided late Thursday near the Hawaiian island of Oahu. The Navy and Air Force are conducting a search-and-resuce mission to find the 12 Marines who were on board the helicopters.
Two Marine CH-53 helicopters collided late Thursday near the Hawaiian island of Oahu. The Navy and Air Force are conducting a search-and-resuce mission to find the 12 Marines who were on board the helicopters.Bullit Marquez/Associated Press file photo

There was no immediate word on what caused the crash or if any survivors have been found.

The transport helicopters each had a crew of six from Marine Corps Base Hawaii and crashed just before midnight Thursday, officials said. No other passengers were aboard the CH-53Es, which came from the 1st Marine Aircraft Wing, Marine Capt. Timothy Irish said.

A Coast Guard helicopter and C-130 airplane spotted a debris field 2½ miles offshore early Friday. The debris covers an area of 2 miles, Irish said.

The search includes aircraft from the Navy and Air Force, a Honolulu Fire Department rescue boat and Coast Guard cutters, officials said.

“It is a true search-and-rescue effort, and it is ongoing,” Irish said just before daybreak on Oahu, where a steady rain was falling on the North Shore.

A swell approaching the area will bring dangerous 30- to 40-foot waves to beaches and 10- to 20-foot seas near the rescue operation, National Weather Service meteorologist Matthew Foster said. Winds will be relatively calm at 10 mph or less.

The crash comes less than a year after the Marine Corps’ new hybridized airplane-and-helicopter aircraft crashed during a training exercise, killing two Marines. The MV-22 Osprey went down last May with 21 Marines and a Navy corpsman on board.

In 2011, one serviceman was killed and three others were injured when a CH-53D Sea Stallion chopper crashed in Kaneohe Bay, Hawaii.

Associated Press writers Caleb Jones in Honolulu, Bob Lentz in Philadelphia and Mark Thiessen in Anchorage, Alaska, contributed to this report.