KUALA LUMPUR, Malaysia (AP) — Malaysian authorities searched Tuesday for 14 missing Indonesians after a boat carrying over 30 people sank.

The maritime office in central Perak state said that 23 people were rescued Monday by a local fishing vessel after the boat capsized off the island of Pangkor in Perak, adding it was believed to be carrying “undocumented migrants.”

Perak maritime chief Capt. Mohamad Shukri Khotob said the fishing vessel called for help after finding the people floating at sea before dawn. The search and rescue operation, which began Monday, would continue until all missing individuals were located, the statement said. A total of 37 people were believed to be on board, he said.

Mohamad Shukri said the victims were believed to have departed from Kisaran, Indonesia, on May 9 and were headed to multiple territories in Malaysia, including Penang, Selangor, and Kuala Lumpur.

The 23 survivors were handed over to marine authorities for questioning.

Malaysia has long been a destination for Indonesian workers seeking better job opportunities. Many attempt to enter the country illegally via sea routes, often in overcrowded and unsafe vessels, risking accidents and loss of life. Indonesians make up the large bulk of foreign labor in Malaysia, predominantly in plantations and construction.