Two fishermen were killed and four went missing Tuesday after a fishing vessel caught fire off South Korea's easternmost islets of Dokdo.
Six crewmen, including the captain of "Munseong 103" were rescued, but two of them died soon after, officials said.
Two South Koreans and two Vietnamese went missing, Yonhap News Agency reported.
Coast guard vessels, planes and private fishing boats have been deployed to search for the missing four.
The fire is believed to have started in the engine room, though the reason is still under investigation, a coast guard official said.
The Munseong 103 was fishing for the fugu fish, an Asian delicacy, near Dokdo, just before the accident.
It had embarked from the southernmost island of Jeju Dec 16 and had been scheduled to return to a port in North Gyeongsang province Jan 2.
