HA LONG, Vietnam: Super Typhoon Yagi ripped roofs off buildings, sank boats and triggered landslides in Vietnam, leaving nine people dead as of Sunday, after tearing through southern China and the Philippines.

A family of four was killed in a landslide in the mountainous Hoa Binh province of northern Vietnam early Sunday morning, according to state media.

The landslide happened around midnight, after several hours of heavy rain brought by Yagi, when a hillside gave way and collapsed onto a house, VNExpress said, citing local authorities.

The home's 51-year-old owner escaped but his wife, daughter and two grandchildren were buried, their bodies recovered soon after.

Yagi, which has devastated infrastructure and uprooted trees, made landfall in northern Vietnam on Saturday, packing winds exceeding 149 kilometres (92 miles) per hour.

Four people were killed Saturday as roofing flew through the air, disaster management authorities said.

A man in Hai Duong province was killed Friday when heavy winds brought down a tree.

Several areas of the port city of Hai Phong were under half a metre (1.6 feet) of flood waters on Sunday, and electricity was out, with power lines and electric poles damaged, according to AFP journalists.

At Ha Long Bay, a UNESCO World Heritage site about 70 kilometres up the coast from the city, fishermen were in shock as they examined the damage Sunday morning.

At least 23 boats were seriously damaged or sunk at the Hai Au boat lock on Tuan Chau island, according to local residents.

Rooftops of buildings were blown off and motorbikes were left toppled over in piles of building rubble and glass, AFP journalists observed.

Pham Van Thanh, 51, a crew member of a tourist boat, said all the vessel's crew remained on board since Friday to prevent it from sinking.

"The wind was pushing from our back, with so much pressure that no boat could stand," he told AFP.

"Then the first one sank. Then one after another.

"I have been a sailor for more than 20 years and have never experienced such a strong and violent typhoon," he said.

Before hitting Vietnam, Yagi tore through southern China and the Philippines, killing at least 24 people and injuring dozens of others.

Typhoons in the region are now forming closer to the coast, intensifying more rapidly, and staying over land for longer due to climate change, according to a study published in July.

  - AFP