Helicopters hoisted 23 crew members from a listing cargo ship to safety overnight, ending a daylong rescue effort as 10-foot waves slapped the ship's tilting deck hundreds of miles off Alaska's Aleutian Islands.

Tuesday morning, with the crew safe on Adak Island, the Coast Guard and the ship operators turned their attention to trying to salvaged the massive car carrier.

The 654-foot Cougar Ace was floating on its side, unattended until a Coast Guard cutter arrived later in the day to monitor it, said Petty Officer Richard Reichenbach. He said the fate of its cargo of nearly 5,000 cars was unknown, but said officials believe the secured vehicles are still on board.

"It's like a giant parking lot inside," Reichenbach said. "I think the worst thing that could have happened is they broke loose and are all piled up on top of each other."

The Cougar Ace had been carrying cars from Japan to Canada when it began tilting to its port side late Sunday night. The crew sent out an SOS, but the nearest Coast Guard ship was a day's journey away.

By the time a Coast Guard aircraft arrived and was able to drop three life rafts for the crew Monday morning, the ship was at an 80 degree angle, nearly on its side, officials said. The roiling waters shoved the rafts underneath the dipping port side of the ship before the crew could secure them.

Rescuers tossed another raft toward the higher starboard side, but it was a 150-foot drop to the water.

A merchant marine ship crew that was nearby was unable to rig a line to the cargo ship, and the Cougar Ace's crew was losing power in its hand-held radio.

The helicopters appeared to the crew's best chance for survival.

"We made the decision to cram in everybody," said Master Sgt. Sal Provenzano with the Alaska Rescue Coordination Center.

In a daring rescue, the crew members, who had donned survival suits aboard their troubled ship, were hoisted Monday night into two National Guard Pave Hawk helicopters and a Coast Guard helicopter, then flown 230 miles north to Adak Island. One crew member with a broken ankle was to be flown by plane to Anchorage, Provenzano said.

The Singapore-flagged Cougar Ace — owned by Tokyo-based Mitsui O.S.K. Lines — was carrying vehicles from Japan to Vancouver, British Columbia, said Greg Beuerman, a spokesman for the ship owner.

He said Tuesday the company was in talks with a salvage company, discussing several options for saving the vessel. It still wasn't clear what had caused the ship to list.

The ship had been caught in rain squalls and 8- to 10-foot seas when it began to list. From Coast Guard aircraft circling overhead, officers spotted a 2-mile oil sheen in the choppy water. The ship had been carrying 430 metric tons of fuel oil or 112 metric tons of diesel fuel, and it wasn't clear how much had spilled into the northern Pacific Ocean.

Early on, the Coast Guard had alerted the clinic at the small town of Adak — a former Naval air station on the island of the same name — to gear up for treating at least one broken ankle and possible hypothermia cases.

Nurse practitioner Michael Terry said residents hustled to set up cots and blankets at the community center, prepare food and coffee, gather donations of warm clothing. The clinic rounded up emergency medics and braced for action.

"We actually were preparing to have an air disaster drill at the airport (Tuesday) so we moved it up a day," Terry said.