At least 27 people have died and dozens are missing after a tourist boat carrying more than 50 capsized in Vietnam’s Ha Long Bay, state media reported.

The vessel was carrying 48 passengers and five crew members when it capsized on Saturday because of sudden heavy rain as it toured the UNESCO World Heritage site, the Dan Tri news site said. 

VNExpress news site reported boarder guards had rescued 12 people. 

Most of those on board were families visiting from the capital Hanoi, with more than 20 children among the passengers, VNExpress said.

Ha Long Bay is one of Vietnam’s most popular tourist destinations, with millions of people visiting its blue-green waters and rainforest-topped limestone islands each year.

Last year 30 vessels sank at boat lock areas in coastal Quang Ninh province along Ha Long Bay after being pounded by strong wind and waves brought by deadly Typhoon Yagi.

AFP