MANILA, Philippines (AP) — At least six crewmembers of a fishing boat were killed when an explosion and a fire hit their vessel at sea off a central Philippine province, coast guard officials said Thursday, adding six others were rescued.

Surviving crewmembers, including the skipper of the F/B King Bryan, were still being treated at a hospital or were too traumatized to tell investigators what set off the explosion and fire onboard the vessel Wednesday night off Naga city in Cebu province, coast guard officials said.

One of the injured crewmen was in critical condition at a hospital in Cebu, the coast guard said.

The wooden-hulled boat, which had bamboo outriggers, apparently developed engine trouble before an explosion and a fire engulfed the vessel, injuring crewmembers and forcing others to jump into the sea in panic. A passing tugboat helped put out the blaze and a coast guard search and rescue operation was launched, coast guard officials said.

Sea accidents are common in the Philippine archipelago because of frequent storms, poorly maintained boats, overcrowding and spotty enforcement of safety regulations.

In December 1987, an overcrowded ferry, the Dona Paz, sank after colliding with a fuel tanker, killing more than 4,300 people in the world’s worst peacetime sea disaster regarded by some as Asia's Titanic.