Eight people were killed after a boat carrying 48 passengers including children sank off Indonesia’s Kalimantan island on Monday, rescue officials said.

The national rescue agency said in a statement that 13 passengers remained missing while the rest had been rescued.

The boat was on its way from Tanjung Selor to Tarakan on the Indonesian side of Borneo island, when it overturned and sank. It was not immediately clear what caused the accident.