Rescuers also were waiting to learn the fate of the downed chopper and whether fuel had spilled when the freighter went aground and split apart on a remote shore of Unalaska Island in the Aleutian chain.

"There are so many things need to look for and get a handle on, but we're battling inclement weather and long distances," said Chief Petty Officer Darrell Wilson.

Four others on the helicopter - three Coast Guard personnel and one crew member - were picked up by another helicopter participating in the rescue, the Coast Guard said. They were taken to Dutch Harbor on nearby Unalaska Island for medical treatment.

Coast Guard officials said the crew member was treated for a neck injury. No injuries among the Coast Guard personnel were reported.

Two other people who had stayed behind on the ship were rescued separately, as were 18 other crew members taken off the ship earlier Wednesday.

The Coast Guard had been struggling to help the 738-foot freighter, the Selendang Ayu, since Tuesday when it began drifting after its main engine broke down. But 25-foot swells and 30-knot winds hampered their effort.

The freighter, which was carrying a load of soybeans, is owned by Singapore-based IMC Group and is registered under a Malaysian flag. Its crew was Filipino and Indian, the Coast Guard said.

Wilson said the air search was set to begin again at 9:30 a.m. AST Thursday for the six missing. The water temperature was about 43 degrees and the waves were as high as 20 feet.

"The survival time is right around three hours in those conditions," Rear Adm. James Olson, commander of the Coast Guard in Alaska, said Wednesday.

Olson said he did not know whether the crew members were wearing survival gear. The cause of the crash was not immediately known.

The carrier's 440,000 gallons of heavy bunker oil had been transferred to inboard tanks and the fuel heaters were turned off to thicken the fuel, so in the event of a spill it would not disperse, Petty Officer Thomas McKenzie said. Unalaska Island, about 800 miles southwest of Anchorage, is home to sensitive wildlife habitat and fisheries.

The amount of spillage, if any, was not known Thursday morning, Wilson said. The Coast Guard was transporting an oil containment boom to Dutch Harbor.

A tug boat had attached a line to the freighter on Tuesday evening, securing it for 12 hours. But then the line broke and the vessel resumed its path to the Unalaska Island shore.

The crew of the Selendang Ayu dropped anchor when it reached shallow water, but it was lost in the rough seas after just a half hour.

The crew later dropped its other anchor, which for a while held the freighter four-fifths of a mile from shore, Olson said.

Sometime around 6 p.m. Wednesday, the captain of the freighter requested the remaining crew member be evacuated from the vessel, as the anchor had begun to give way and the freighter had started to flood.

Eight were on board, after 18 had been previously evacuated.

The helicopter crashed into the sea soon after picking up crew members, leaving behind the captain and a Coast Guard rescue swimmer. They were later rescued by the second helicopter. Around 7:15 p.m., the freighter broke in half.

The Selendang Ayu is a single-deck bulk carrier built in China in 1998. It is owned by IMC Transworld, a subsidiary of IMC Group.

Company representatives are in Dutch Harbor and have met with Coast Guard officials, Olson said.

Olson said all Coast Guard personnel had been accounted for.