A tourist boat capsized during a sudden thunderstorm in Vietnam on Saturday afternoon, killing 38 people and leaving seven others missing.

The Wonder Sea boat was carrying 48 passengers and five crew members on a sightseeing the tour of Ha Long Bay, a popular destination for visitors, state media reported.

Rescue workers saved 12 people and recovered 38 bodies near the site of the incident, the VNExpress newspaper said. Several people remain missing.

“At least 38 of those on board have been confirmed dead and 10 rescued,” the government said in a statement.

The official Vietnam News Agency reported that all the tourists were Vietnamese, including several children.

The boat overturned as a result of strong winds, the newspaper said. A 14-year-old boy was among the survivors. He was rescued after four hours trapped in the overturned hull.

The newspaper said most of the passengers were tourists, including about 20 children from Hanoi, the country’s capital.

A tropical storm is also moving toward the area. A national weather forecast said Storm Wipha was expected to hit northern Vietnam, including the coast of Ha Long Bay next week.