The Coast Guard suspended its search Tuesday evening for 12 missing Marines off Oahu after no survivors were found during five days of continuous searching in the aftermath of a two-helicopter crash.

“The decision to suspend this search without finding survivors is particularly difficult,” said Coast Guard Capt. Jim Jenkins at a news conference at Marine Corps Base Hawaii at Kaneohe Bay on Tuesday afternoon. “Our thoughts and prayers are with the Marine Corps Helicopter Squadron 463 and particularly with families and loved ones of those missing.”

Jenkins said the Coast Guard suspended the search after conducting an extensive review of the case and poring over computer models and other findings.

He said rescuers found a widespread debris field on the seafloor with parts of aircraft in about 325 feet of water some 2 miles off Haleiwa.

Some of the wreckage from the seafloor, as well as debris on the ocean surface, has been recovered. The Coast Guard also recovered the four life rafts that were on board the two CH-53E Super Stallion helicopters and said there was no sign that anyone had been inside the rafts.

The Coast Guard handed the case over to the Marines, who will conduct a recovery operation.

Brig. Gen. Russell Sanborn, commanding general of the 1st Marine Aircraft Wing, said an aviation mishap board is investigating the cause of the crash.

“To the families that are most affected by this, our prayers and our support are to them, and that’s our No. 1 goal and our focus,” he said.

He thanked the civilian searchers for their efforts and the public for showing support by providing rescuers with food and information.

Authorities searched more than 53,600 square miles at sea. Honolulu firefighters, lifeguards and Marines conducted an extensive shoreline search.

Battling large surf, lifeguards scoured more than 300 miles by personal watercraft in a search pattern between Kaena Point and Kahuku. Dozens of Marines walked the shoreline from Kaena Point to Kahuku, looking for debris.

Other agencies assisting the Coast Guard were the Navy, Army, Hawaii Army National Guard, police and paramedics.

The Coast Guard searched with an MH-65 Dolphin helicopter, an HC-130 Hercules airplane and two patrol boats. The Navy assisted with a P-3 Orion patrol plane, a helicopter and four vessels. The Navy’s Mobile Diving and Salvage Unit 1 searched underwater with a remotely operated vehicle.

Witnesses reported the two helicopters with six Marines each went down in a fireball at about 10:40 p.m. Thursday and may have collided.

Sanborn said the helicopters did not have voice or flight data recording equipment on board.