JAKARTA: A boat carrying 96 people from Malaysia to Indonesia sank on Wednesday, killing at least 18, Indonesian police said.

The boat, from Johor, sank off Indonesia’s Batam island when it was hit by big waves, police said. The passengers were believed to be illegal workers returning to Indonesia. At least 39 people were found alive.

“Search and rescue efforts continue to find the rest of the passengers,” police spokesman Airlangga said.

The boat set sail from the southern Malaysian state of Johor and was headed towards Indonesia’s Batam island, just south of Singapore, the Indonesian national disaster mitigation agency said in a statement.

The boat crashed into a reef after being hit by big waves and strong wind, and sank at around dawn, the disaster agency said.

There were 39 survivors.

A helicopter would be sent out to search for bodies, the region’s police chief, Sam Budigusdian, told reporters. A baby was among the 18 confirmed dead, he said.

Zainul Arifin, one of the survivors who worked at an oil palm plantation in Malaysia, said he was sitting at the back of the boat when sea water started coming aboard. “I had to jump off and start swimming,” Arifin told Reuters in the port town of Nongsa on Batam.

Many Indonesians work in Malaysian factories and plantations.

Boat accidents are common in Indonesia, a sprawling archipelago of more than 17,000 islands.