Rescuers plan to search at least one more day for 12 Marines missing after their two helicopters crashed off Oahu’s North Shore last week, Mayor Kirk Caldwell said Monday night.

He said rescuers want to search a fifth day, to this evening, and evaluate at that point whether to continue with the search mission.

No survivors had been found by Monday afternoon, but the Coast Guard recovered all four life rafts that had been on the two Ch-53E Super Stallion helicopters.

Coast Guard Lt. Scott Carr said the cutter Kiska recovered the last life raft off Kahuku on Monday after it was spotted by a good Samaritan the day prior. Some debris consistent with a military aircraft has also been found.

Caldwell visited the search command post at Haleiwa Alii Beach Park on Monday before departing that evening for a conference in Washington, D.C. He said he wanted to thank the rescuers, especially county employees “who have given their all.”

“I just saw everyone giving what they possibly could to do what they can,” he said. “There’s a real sense of sadness, but complete cooperation by everyone.”

The Coast Guard is leading the search with help from the Navy, Marines, Honolulu police, firefighters, paramedics and lifeguards.

Caldwell praised lifeguards for working with little rest while combing through large surf on personal watercraft. They are able to maneuver in places where “other agencies just don’t have the ability or the experience or expertise,” Caldwell said. “I’m very proud of that.”

An Ocean Safety spokeswoman said lifeguards have searched 250 miles in a pattern between Kaena Point and Kahuku on personal watercraft since Friday and planned to continue searching today.

Caldwell said county workers were the first on the scene after the two helicopters crashed late Thursday night. A Honolulu Fire Department boat was in the water, and a police helicopter was shining a searchlight on the surface to locate debris.

He said county first responders were gathering debris to turn over to the military when they showed up.

An inflated life raft with a flashing strobe light was discovered the first night in the debris field along with fuel.

Caldwell said he was told the life rafts are designed to open up when the helicopter hits water, but it was not clear whether that is the reason the life rafts were deployed.

The Coast Guard said there was no indication anyone had been aboard the rafts.

Marines also walked the entire coastline from Kaena Point to Kahuku searching for debris, Caldwell said. Sixty-five Marines searched the shoreline Monday.

Caldwell said police are working with the military to catalog any debris that is found along the shore- line and bring it to the command post.

Caldwell said he offered the military the use of Haleiwa Alii Beach Park for as long as it needs, and authorities will probably use a building at the beach park for the rest of the week. But the command footprint will shrink, and part of the park will be reopened, he said.

During his 90-minute visit to the command post, the community also stepped up by bringing malasadas, pizzas and water, Caldwell said.

By Monday morning the Coast Guard had searched more than 24,000 square miles off West Oahu and the North Shore.

The Coast Guard said it would continue searching overnight Monday with an MH-65 Dolphin helicopter and a HC-130 aircraft. The Navy searched Monday with a P-3 Orion patrol plane and a warship, joining police and fire helicopters.

Navy Mobile Diving and Salvage Unit 1 was also searching underwater of the last known position of the helicopters about 2.5 miles off Haleiwa. The unit used a remotely operated vehicle to search on Sunday and Monday but didn’t recover any debris, the Coast Guard said.

Carr, the Coast Guard lieutenant, said a Navy salvage ship was assisting the dive unit as an operations platform and was not using sonar to search for the wreckage.

He said the area where the helicopters are thought to have crashed is about 200 to 350 feet deep.

Marines said the helicopters did not have locating beacons similar to commercial aircraft.

“Our focus is to locate these Marines and know with absolute certainty we’ve thoroughly canvassed every location we might find them,” Carr said in a statement Monday.

The Marines are investigating the cause of the crash.