A fishing boat sailing off the coast of Korea’s southernmost island of Jejudo caught fire and sank on Monday, leaving six people dead and one missing, according to Jeju Coast Guard.

According to Kim, the 37-year-old captain of the boat, the fire broke out around 4:55 a.m. while the boat was sailing in waters 108 kilometers southwest of Jeju City.

Kim said he ordered his nine crew members to jump off the vessel after the fire got out of hand. In the process, a 50-year-old sailor surnamed Jeon went missing.

The crew was rescued by fishing boats and a coast guard ship. The injured men were moved to a hospital in nearby Jeju City, but six ― all five of the Indonesians and a 45-year-old Korean sailor surnamed Kim ― died during treatment.

The boat sank around 7:15 a.m., just over two hours after the fire broke out.

Kim and another unnamed sailor are being treated at a hospital in Jeju City.

Officials said they are searching the area for the missing sailor with the help of seven civilian fishing boats.

The coast guard explained that the sunken boat was more vulnerable to flames than aluminum vessels because it was made of fiber-reinforced plastic, a composite material favored for its strength and light weight.

By Yoon Min-sik (minsikyoon@heraldcorp.com)