At least 34 people, including eight children, have died after a tourist boat capsized in Vietnam’s Ha Long Bay on Saturday, according to state media reports.

The vessel, which was carrying 48 passengers and five crew members on a sightseeing excursion, was overturned by strong winds and large waves during a sudden thunderstorm, Vietnamese outlets reported.

Rescue operations, involving naval commandos from Quang Ninh province in northeastern Vietnam, recovered dozens of bodies and managed to save at least 10 people.

Among those rescued was a young boy who had remained in the water for several hours.

“It’s the most tragic incident I’ve witnessed in Ha Long Bay in over two decades,” said Bui Cong Hoan, deputy chair of the Ha Long Tourist Boat Association.

Authorities confirmed that all those on board were Vietnamese nationals. Images circulated by local media showed the vessel fully capsized, its hull protruding above the water.

In one particularly heartbreaking case, only the mother survived out of a family of four.

Prime Minister Pham Minh Chinh has directed civil defense units and both the Defense and Public Security Ministries to intensify the search and rescue efforts, according to Vietnam’s official government portal.

The boat had been returning from a tour of Dau Go and nearby limestone caves in Ha Long Bay a UNESCO World Heritage Site when the storm struck. The vessel was among the many tourist boats that operate daily in the popular bay, officials said.