At least 31 people died in a massive fire that swept through an inter-island  ferry at night in the southern Philippines, authorities said on Thursday.

The Philippine Coast Guard and local fishermen saved 195 passengers and 35 crew from the blaze. The Lady Mary Joy 3 ferry was travelling from Zamboanga City on Mindanao Island to Jolo Island in Sulu province when the fire broke out late Wednesday, prompting passengers to jump overboard, an AFP report from Manila cited disaster officer Nixon Alonzo as saying.

Authorities have yet to identify the cause of the fire that started close to 11 p.m. on Wednesday off the island of Basilan, when many of the passengers were asleep in air-conditioned cabins on the ferry’s lower deck.

The bodies of some passengers who died in the fire were found inside an air-conditioned cabin during an ongoing search of the ferry.

“People panicked because they were asleep when the fire happened,” citing witness accounts.

As the fire spread, the captain ran the vessel aground “so many more could survive since it would be easier to swim to shore,” Commodore Rejard Marfe from the Philippine Coast Guard told AFP news agency.

Photos released by the coast guard showed one of its vessels spraying water on the burning ferry as personnel in smaller boats picked up passengers from the sea.

The Philippines, an archipelago of islands, is served by a shoddy sea transport, with overcrowded ferries that often meet with accidents.