South Korea ? Coast guard boats and helicopters searched today for 14 sailors feared dead in chilly waters off South Korea after their cargo ship was thought to have sunk in high seas.

The ship, carrying 2,000 tons of nitric acid, went missing after it sent out a distress signal early Tuesday off Yeosu, 280 miles south of Seoul. One sailor was rescued but the remaining 14 crew members had yet to be located.

“Unfortunately, we didn’t find any survivors,” coast guard spokesman Kang Byung-mun said after overnight search and rescue works. “We believe the ship sank.”

The nitric acid on board was not likely to cause environmental damage because it easily dilutes, coast guard officials said.

The coast guard has found 18 drum cans and several life jackets and boats believed to be from the ship, he said. No wreckage has been found yet, Kang said.