SEOUL - A South Korean fuel tanker sank Sunday after an explosion on board, leaving five crew members dead and six missing, the coastguard said. The 4,191-tonne ship carrying 11 S Koreans and five Myanmar citizens sank near Jawol island, about 32km off the western port of Incheon where the vessel had unloaded its cargo, a coastguard spokesman told AFP. Yonhap news agency reported that the explosion was likely caused by gases leaking from the ship’s oil tanks, citing an official from the firm that owns the vessel. “We believe that something went wrong during the process to take out remaining gas in the oil tank,” the Doora Shipping official told the agency.