Official says 37 people were on board the vessel when it ran into trouble off the coast of Borneo island.

At least four people have died and dozens more are missing after a fishing boat sank off the coast of Borneo island, according to an Indonesian official.

Iman Saputra, a spokesperson for the country’s search and rescue agency, told Reuters news agency on Friday that there were 37 people on board the vessel, four of whom had been found dead and two had survived

“Rescue efforts will go on for the next four days,” Saputra said, noting that the agency had deployed 35 people to search for those missing.

“The obstacles are high tides and strong winds,” added the spokesperson, who is based in Banjarmasin, the capital of South Kalimantan province, near the site of the sinking.

The vessel had left the town of Pekalongan on Java island three days before running into trouble, Saputra said.

The vessel lost radio contact and officials only became aware of the accident on Friday after another boat found four bodies and two survivors near Matasiri island in the Java Sea, according to local port official Mugen Suprihatin Sartoto.

“We think that the boat’s distress radio beacon was broken,” Sartoto told Metro TV.

Marine accidents are common in Indonesia, an archipelago nation of more than 17,000 islands, where many use ferries and other boats to travel despite poor safety standards.