A large-scale search and rescue operation was underway off the western Philippine island of Palawan on Thursday after a passenger ferry caught fire, killing five people and leaving dozens of passengers missing.

The Philippine Coast Guard (PCG) said multiple vessels and other assets were deployed to search for survivors, while rescue teams were using drift-modelling tools to identify areas where people may have been carried by currents.

Based on the vessel’s manifest, the number of survivors, currently at 43, and the fatalities reported so far, authorities estimated that more than 80 people remained unaccounted for, although the figures could still change.

Coast Guard spokesperson Commodore Noemie Cayabyab said rescuers could not yet enter the vessel, with the search hampered by thick smoke still billowing from the ferry as well as concerns about extreme heat and the risk of explosions.

Drone footage released by the Coast Guard showed the blackened ferry surrounded by clear blue-green waters, with the vessel still generating smoke hours after the fire broke out on Wednesday night.

Cayabyab said the vessel’s manifest listed a total of 117 passengers and 17 crew members. The ferry had departed from Baseco in Manila and was bound for Coron, a popular tourist destination in Palawan known for its diving sites, beaches and island-hopping attractions.

Among the 43 people rescued were two Chilean nationals, said Aileen Ausente, spokesperson for PCG in Palawan, adding that air assets were on standby to help with rescue operations, the weather permitting.

The burned ferry had drifted farther from its original location overnight, carried by currents and winds, adding to the challenges facing rescuers, Cayabyab said.

The cause of the fire is under investigation.

Ferry travel is a common mode of transport in the Philippines, an archipelago of more than 7,600 islands, where millions of people rely on boats to travel between provinces.

The country has a patchy maritime safety record, and many previous ferry disasters have been linked to overcrowding, rough weather and lax enforcement of safety regulations. (CNN)