ANCHORAGE, Alaska – Frustrated by furious winds, mountainous seas, and a mere five-hour window of December daylight, rescuers searched yesterday for six people lost in the Bering Sea after the Coast Guard helicopter that had plucked them from a crippled freighter crashed in the darkness.

The ship they left behind ran aground and split apart, and fuel from the vessel had started leaking. Environmental officials feared that it would become a massive spill.

Searchers hoped the missing crew had somehow lived through the night, but 43-degree waters reduced survival estimates to about three hours. Rescuers were hampered by seas that swelled to 20 feet and winds that howled at 35 mph.

“Those high winds make flying difficult and is going to make for choppy seas,” Coast Guard Chief Petty Officer Roger Wetherell said. “If somebody is out there riding a wave, you may not see them.”

Searchers reported improving visibility, but limited daylight forced them to wait until after sunrise at 10 a.m. to resume rescue flights.

The rescue helicopter crashed into the sea Wednesday carrying 10 people – seven crew members and three Coast Guard personnel. Four were rescued by a second helicopter and in good condition yesterday. The cause of the crash was not known. The missing crew members included one Filipino and five people from India.

The freighter’s captain and a rescue swimmer who had remained on the vessel were also rescued shortly before the ship broke up. Eighteen other crew members were previously evacuated.

Rear Admiral James Olson said he did not know whether the missing crew members were wearing survival gear. The 738-foot freighter was carrying 480,000 gallons of heavy fuel oil and 21,000 gallons of diesel fuel.