Rescuers in Indonesia are searching for 25 people who are missing after a cargo boat sank in the Makassar Strait in South Sulawesi province, officials said on Sunday.

A total of 42 people were on board when the vessel sank in bad weather on Thursday morning while travelling from a seaport in Makassar to Kalmas Island in Pangkep Regency, said Djunaidi, the head of the provincial search and rescue agency. Like many Indonesians, Djunaidi goes by only one name.

Seventeen people were later rescued, including some by two tugboats that were at sea at the time of the incident.

Djunaidi said the search and rescue agency received new information about the location of the sunken boat on Saturday and dispatched crews to the area.

Two motor boats and a search and rescue boat, along with local fishing boats and Indonesia air force helicopters, are involved in the search for the missing people.

The vessel that sank was initially said to be a passenger ferry, but Djunaidi later clarified that it was a cargo boat carrying construction materials. There was a crew of six along with 36 passengers who had asked for a ride on the boat.

Ferry tragedies are common in Indonesia, an archipelago of more than 17,000 islands, where ferries are often used as transport and safety regulations can lapse.

In 2018, an overcrowded ferry carrying about 200 people sank in a deep volcanic crater lake in North Sumatra province, killing 167 people.

In one of the country’s worst recorded disasters, an overcrowded passenger ship with 332 people on board sank in February 1999. There were only 20 survivors.