Six crew members died and one is still missing after a fish-processing vessel sank in the icy waters off an Alaskan island chain. Four crew members were rescued after spending about 15 hours in a life raft in the frigid conditions of the region, the U.S. Coast Guard said.

The bodies of the six dead members of the vessel were recovered, but of the 11-man crew, one is still missing. Coast Guard officials said the four crew members had managed to survive and endure the extreme weather condition because they were equipped with survival suits, they were in a good physical condition and they managed to keep one another semi-warm.

"They were in good spirits and in good shape," said Coast Guard Petty Officer Levi Read. "They asked to stay, so they could continue to help with the search."

The life raft with the four survivors was reportedly discovered near the Amchitka Pass, which links the Bering Sea to the Pacific Ocean about 1,400 miles southwest of Anchorage, The Associated Press news agency reported. The water temperature in that area was of 43 degrees.

The U.S. Coast Guard received a signal at 1 a.m. from the Katmai and then sent a search helicopter and a C-130 airplane to search for survivors. No mayday call was heard at the Coast Guard. The fishing vessel may have made the call but wasn’t heard due to the remote area from which it was made.

"It's hard to say whether they tried or not," Read said.

It’s not clear yet what happened with the 93-foot Katmai. The vessel was carrying a load of cod and heading toward Dutch Harbor on Unalaska Island, 800 miles southwest of Anchorage. One fishing vessel joined the search and another was expected, Coast Guard officials said.

One of the two missing bodies was discovered by the fishing vessel that joined to help the Coast Guard. The crew of the fishing vessel also found debris, survival suits, fishing gear, a buoy and a life ring.