Malaysia’s maritime authorities searched Tuesday for 14 Indonesians missing after a migrant boat sank off Pangkor island in Perak, according to a Perak maritime office statement. Authorities said the boat had carried more than 30 people, and they began a search-and-rescue operation after the vessel capsized offshore.

The rescue was carried out Monday by a local fishing vessel, which found people floating at sea before dawn and alerted authorities, Perak maritime officials said. In total, authorities said 23 people were rescued and taken into custody for further processing.

Perak maritime chief Capt. Mohamad Shukri Khotob said in the statement that officials believed 37 people had been on board and that the missing count was 14. The statement said the search and rescue operation would continue until the missing individuals were located.

Authorities said the boat was believed to be carrying “undocumented migrants.” The maritime office said the victims were believed to have departed from Kisaran, Indonesia, on May 9, and were headed to multiple destinations in Malaysia.

The statement listed those destinations as including Penang, Selangor and Kuala Lumpur, and it said the 23 survivors were handed over to marine authorities for questioning.