Malaysian rescuers were searching on Tuesday for 14 Indonesians missing after a boat believed to be carrying undocumented migrants sank off Pangkor Island, the latest emergency along a dangerous sea route used by workers trying to enter Malaysia by boat.

The Malaysian Maritime Enforcement Agency said 23 people, comprising 16 men and seven women, had been rescued after the boat went down in waters off the resort island in Perak state early on Monday.

Authorities believe 37 people were on board, all Indonesian nationals. No deaths had been reported as of Tuesday, but the remaining passengers had yet to be identified.

Perak maritime director Mohamad Shukri Khotob said the agency was alerted around 5.30am local time on Monday after a local fisherman found victims floating at sea and calling for help.

“Initial investigations found that the total number of undocumented migrants on board the boat was 37,” he said in a statement. “So far, 23 victims have been rescued, while the remaining victims have yet to be identified, and search operations are continuing.”

A local fishing vessel rescued the survivors before they were escorted by a marine police boat to the Kampung Acheh marine police jetty for documentation and further investigation. They were later handed over to authorities at the Manjung district police headquarters.