GUNSAN (Yonhap News) ― Nine fishermen were killed and one was missing when their boat caught fire and sank off South Korea’s central west coast Saturday, maritime police said.

The fire started at about 4:30 a.m. on the 20-ton fishing boat in waters about 24 kilometers southwest of Gunsan, according to the police. Gunsan, a port city, is 274 kilometers southwest of Seoul.

The police said they received a distress call from the boat at about 5:20 a.m.

The boat’s only survivor so far said the fire started from the engine room and that the crew members tried to put it out with seawater.

The fire spread quickly and out of control when the hose to a fuel tank burst, the 50-year-old fisherman, identified only by his surname Lee, was quoted by the police as saying.

The police said they were still investigating the exact cause of the fire.

The accident forced all 11 crew members on board to jump off the boat. Ten, including Lee, were pulled out of the water about two hours later, but nine of them were pronounced dead.

Search efforts were under way for the one missing crew member, they said.

“It appears the people died because of hypothermia caused by excessively low water temperature,” a police officer said.

The police blamed a late report for the large number of casualties.

Thick fog that caused poor visibility also seems to have played a part in hampering search and rescue efforts, they added.