KUALA LUMPUR， Malaysia — At least 16 people were killed and 20 others were missing after a boat carrying at least 50 Indonesian migrants sank in the South China Sea before dawn on Wednesday， Malaysian officials said.

The boat capsized in bad weather around 4:30 a.m. off the coast of Tanjung Balau， a beach town in the southeastern Malaysian state of Johor， an official with the country’s Maritime Enforcement Agency said. Waves were between 12 and 14 feet high at the time of the accident， he said.

Fourteen people were rescued after the agency deployed a helicopter and two boats for a search-and-rescue operation just before 9 a.m.， said the official，Simon Templer Lo，a deputy director in Johor. One of the rescued was in critical condition.

Bernama，Malaysia’s national news agency，posted a photo on Twitter that it said showed people on a beach recovering the capsized boat from the surf.

A spokesman for the Malaysian Army’s Third Infantry Division later said that all the passengers onboard were Indonesian. He said they had sailed from the Indonesian island of Batam，which borders the Singapore Strait.

Several survivors said they were from Lombok，an island east of Bali，and had traveled to Batam to enter Malaysia，Mr. Simon said. He added that the survivors would be questioned before being deported to Indonesia.

Eleven bodies were recovered on Wednesday， and five more — four male and one female — were found on Thursday about 1.5 miles from where the boat was recovered.

Batam is close enough to Singapore and neighboring Malaysia that until the pandemic it had been connected to the city-state by regular ferry service.

Boat accidents are common in the region，and some have involved Rohingya refugees.

Over the years，thousands of Rohingya people have attempted the perilous crossing by boat to Malaysia from Myanmar，where they face ethnic persecution，or from Bangladesh，where they often live in poverty. They typically head southeast through the Straits of Malacca to Malaysia’s west coast.