Rainfall from the storm inundated the capital Hanoi, bringing large parts of the city to a standstill and rerouting dozens of flights.

Bualoi made landfall in central Vietnam late Sunday, packing winds of 130 kilometres (80 miles) per hour, and remained over land for almost 12 hours.

It arrived in Vietnam after battering parts of the Philippines, where it killed 27 people and forced 400,000 to evacuate their homes.

"This typhoon -- the tenth that hit Vietnam this year -- was a serious natural disaster, bringing a combination of strong winds, huge flash floods and widespread flooding," said Mai Van Khiem, head of the National Centre for Hydro-Meteorological Forecasting.

Its lengthy duration over Vietnam was "very rare," Khiem added.

By Tuesday, the typhoon and its aftermath, had killed 26 people and injured more than 100 in Vietnam, the environment ministry said. Thirty others were missing.

More than 136,000 houses were damaged, and several thousand families were stranded in central Ha Tinh province, the ministry added.

"I have not experienced such a strong typhoon in several decades," Le Hong Luyen, 62, from Nghe An province told AFP. "My house and garden are all flooded."

The storm also devastated 225 square kilometres (about 85 square miles) of rice fields and other cropland, uprooted tens of thousands of trees and downed electrical poles, causing power outages in several central areas on Tuesday.

Disaster and weather authorities warned of rising river levels and possible landslides in mountainous areas.

- Hanoi: 'a big pool' -

Heavy rain that began late Monday also caused widespread flooding in the capital Hanoi.

"The floodwater reached almost the top of my motorbike. It was a terrible morning," said Hanoi resident Tran Thanh Huong, who spent two hours trying to reach her office on Tuesday morning before giving up.

The flooding was the worst in the city since 2008, and had turned Hanoi into "a big pool," added resident Nguyen Luu Tien.

"Cars and motorbikes were floating everywhere, even in the city centre," the 52-year-old said.

Images on social media showed military trucks transporting children through flooded streets from a secondary school west of Hanoi, as parents elsewhere pleaded on Facebook for similar assistance in the city's north.

"It's just water everywhere here," wrote one mother.

Other schools said they would stay open for students and teachers who could not reach their homes.

Poor visibility caused by the heavy rain forced the rerouting of dozens of flights headed to Hanoi's Noi Bai airport, aviation authorities said.

Vietnam is usually hit by up to 10 storms annually, but forecasters have warned it faces two to three more this year.

Scientists say human-driven climate change is turbocharging extreme weather events like typhoons, making them ever more deadly and destructive.

Storms caused Vietnam $371 million in damage from January to August, triple the amount over the same period last year, the General Statistics Office (GSO) said.

Last September, Typhoon Yagi killed hundreds of people in Vietnam and caused economic losses worth $3.3 billion.