The vessel started taking on water shortly before 3 a.m. after losing control of its rudder 120 miles west of Dutch Harbor, which is on Unalaska Island.
State environmental regulators were notified that the ship was carrying 100,000 gallons of diesel, according to Leslie Pearson, emergency response manager for the Alaska Department of Environmental Conservation. A Coast Guard c-130 crew reported an oil sheen that covered an area of a quarter mile by a half mile, Coast Guard spokesman Ray Dwyer said.
Those on board the Alaska Ranger were heading to Dutch Harbor in a Coast Guard cutter and the doomed vessel's sister ship, the Alaska Warrior. The vessel took part in the rescue operation along with two Coast Guard helicopters that were used to pluck crew members from life rafts, Lane said.
A C-130 also remained to help search for the missing crew member.
Coast Guard Lt. Eric Eggan said it was unknown how or when the four died. The identities of the dead were unknown.
Chuck Harvey, a harbor officer on duty in Dutch Harbor, said his office was notified by the Coast Guard to clear a dock for its arrival, expected around 11 p.m. EDT Sunday.
The Coast Guard also told harbor officials to have an ambulance ready, but didn't specify the degree or nature of any injuries, Harvey said.
"I figure there's quite a bit of hypothermia going on," he said.
The Alaska Ranger is owned by Seattle-based Fishing Company of Alaska. A man who answered the company's phone Sunday afternoon declined to identify himself or comment. He said no one else was available to comment.
"Today, they're all pretty much tied up," he said. Coast Guard Petty Officer Levi Read said the company had sent an insurance adjuster to Dutch Harbor, who was expected to arrive Sunday afternoon.