The typhoon hit Hai Phong and Quang Ninh provinces, packing winds exceeding 149 kilometres (92 miles) per hour, the National Centre for Hydro-Meteorological Forecasting said.

In Hai Phong, metal roof sheets and commercial sign boards were seen flying across the city sky as the typhoon hit.

Further inland in Hai Duong province, a man was killed in the street after heavy winds brought down a tree as the storm approached landfall, according to state media.

"It has been years since I witnessed a typhoon this big," said Tran Thi Hoa, a 48-year-old woman from Hai Phong.

"It was scary. I stayed indoors, after locking all my windows. However, the sound of the wind and the rain was unbelievable," she told AFP.

- Powerful winds -

Before hitting the mainland, the typhoon unrooted hundreds of trees on Co To island, about 80 kilometres from mainland Quang Ninh.

Several office buildings, schools and houses on the island were unroofed by the powerful winds.

Signboards lay scattered around the island, while electrical lines were snapped and tangled by the wind.

Local authorities said the typhoon was the most severe to hit the island in decades.

The storm killed at least two people and injured 92 others on southern China's Hainan island before hitting Vietnam

State broadcaster CCTV said Yagi brought winds of more than 230 kilometres (143 miles) per hour, uprooting trees and prompting the evacuation of around 460,000 people.

The storm lashed "Hainan with heavy rain and gusty winds, leaving at least two dead and 92 injured", Xinhua said, citing local authorities.

Vietnamese Prime Minister Pham Minh Chinh called on local authorities to evacuate residents from dangerous areas before the storm hit. He also urged other residents to stay indoors.

- Evacuated -

Around 20,000 people have been evacuated and moved to safer, higher ground in the north of Hai Phong, Thai Binh, and Hanoi, local authorities reported.

Many are being sheltered in schools, kindergartens, and other public buildings.

More than 457,000, many of who are professional men, were mobilised by the Ministry of Defence's rescue and relief department to deal with the fallout from the typhoon.

Some 2,000 vehicles and six planes have been sent to deal with the situation.

Northern Vietnam has been experiencing heavy rains and strong winds since Friday evening, including in the capital, Hanoi.

A woman was killed in the capital on Friday afternoon when a tree fell in the street after heavy rains.

Four airports in northern Vietnam, including Hanoi's Noi Bai International Airport, have been closed, while sailing has been banned since Friday.

Yagi killed at least 13 people in the Philippines this week when it was still classified as a tropical storm.

It caused flooding and landslides on the main island of Luzon before transforming into a super typhoon in recent days.

Southern China is frequently hit by typhoons in the summer and autumn, which form in the warm oceans east of the Philippines and Thailand.

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.