"It took only a few seconds": survivors recount how a sudden storm drowned dozens in Vietnam

HALONG (Reuters) -The thunderstorm came so suddenly that it overturned the boat within seconds, said two survivors of the shipwreck which killed at least 35 people in Vietnam's top tourist spot of Halong Bay and left another four missing.

"It had been raining for 15 minutes, then there was a thunderstorm ... and a huge wave that all of a sudden capsized the boat," said Nguyen Hong Quan, one of 10 survivors of the accident, which happened early on Saturday afternoon.

"It took only a few seconds," he told Reuters on Monday, recalling one of the worst accidents in recent years to hit the UNESCO-protected archipelago, which consists of thousands of limestone islands about 200 km (125 miles) northeast of Hanoi.

Of the 49 people that Vietnam's government said were on the boat, four are still missing. Weather conditions are expected to worsen in the coming hours with the landfall in northern Vietnam of Typhoon Wipha, which skirted the southern Chinese coast over the weekend causing flash floods and landslides.

Authorities were verifying on Monday whether a body found on an islet in the bay was one of the missing people from the accident, according to local media.

The thunderstorm hit large parts of northern Vietnam on Saturday, turning the sky dark in a matter of minutes, with sudden downpours and strong winds felling trees in the capital of Hanoi and temporarily disrupting air travel at the Noi Bai international airport.

Quan, a 40-year-old tourist, said he drifted for about three hours on a wooden chair from the sunken boat before a fishing vessel finally rescued him.

Hanging on the chair together with him were another two people, only one of whom survived.

"One of them was too tired and couldn't hold any longer. What a tragedy," he said.

His account matches that from the second person who survived by holding onto the chair.

"The waves were so strong. One of the other two was too tired and said goodbye to us," Vu Anh Tu, a 25-year-old member of the crew, told Reuters.

He also recalled how the storm hit the boat so suddenly, causing it to overturn "in 15 seconds".

"There was so much loss, including children," he said, confirming reports from authorities that several minors were also on the sunken vessel.

"I don't know if I'll ever work on a boat again," Tu said.

(Reporting by Thinh Nguyen in Halong; Additional reporting by Khanh Vu and Phuong Nguyen in Hanoi; Writing by Francesco Guarascio; Editing by David Stanway)