(UPDATE) AT least six fishermen were killed when an explosion and a fire hit their boat at sea off the coast of the City of Naga, Cebu, coast guard officials said Thursday, adding six others were rescued.

Surviving crew members, including the skipper of the FBCA King Bryan were still being treated at a hospital.

PO1 Joel Baring of Philippine Coast Guard (PCG) Substation Naga told The Manila Times the vessel experienced engine problems before leaving Masbate.

He added that midway through the trip, while the crew was troubleshooting one of the two engines, it exploded and set the vessel on fire.

"The boat captain said they were trying to fix the engine but it sparked and exploded," the officer said in Cebuano.

Baring said that the vessel was bound for Daanbantayan town in northern Cebu to fish.

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 crew members 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.

By 10 p.m. Wednesday, the coast guard had retrieved the bodies of two fishermen. They continued the search but temporarily stopped at around 1 a.m. due to strong waves.

Another two bodies were found at around 5 a.m., and the remaining two were retrieved at almost 8 a.m.

Baring said that five survivors were immediately sent to the city infirmary for treatment, while the other, in critical condition, was sent to Cebu South General Hospital.

He added that they are currently contacting the family members of the victims.

PCG Substation Naga said they were still finalizing the list names of the victims.