Forty-one people believed to be illegal migrants were pulled out of rough seas while eight Indonesians were still missing after their boat capsized off the southern Malaysian state of Johor on Monday.

The boat had been carrying around 50 passengers, apparently smuggled from Malaysia, but the exact number was not immediately known. Authorities were alerted to the incident when a woman made an emergency call, an official from the Maritime Enforcement Agency told AFP.

“The boat was overloaded, and the seas were rough so it sank,” the official said, adding that search and rescue efforts for those still missing were under way. The survivors include 35 men, four women and two children.

Boat accidents along Malaysia’s coast has increased with the influx of people from impoverished countries, such as neighboring Indonesia and Myanmar, usually attempting to enter the country illegally for work.

Last month alone, ten Indonesians, including two pregnant women, drowned when their boat capsized off Johor while nearly 500 people from Myanmar illegally entered Malaysia by swimming ashore from a people-smuggling boat in a separate incident.