Landslides and floods triggered by the typhoon had killed at least 65 people and 39 others were missing in the north, the disaster management agency said on Tuesday, adding 752 people have been injured.
Other northern areas, including the industrial hubs of Bac Giang and Thai Nguyen, which host factories of several multinationals including Samsung Electronics and Apple supplier Foxconn, are also facing severe flooding, state media reported.
It was not immediately clear if the companies were affected.
The typhoon crossed the coast on Saturday in Vietnam's northeast, devastating a large swathe of industrial and residential areas and bringing heavy rains that caused floods and landslides.
Eight people are missing after a bridge collapsed in the northern province of Phu Tho. (EPA PHOTO)
It had previously hit the Philippines and the southern Chinese island of Hainan.
Several rivers in northern Vietnam have risen to alarming levels, leaving villages and residential areas inundated, according to the disaster agency and state media.
A 30-year-old bridge over the Red River in the northern province of Phu Tho collapsed on Monday, leaving eight missing, according to a statement from the provincial People's Committee.
Authorities have subsequently banned or limited traffic on other bridges across the river, including Chuong Duong Bridge, one of the largest in Hanoi, according to state media reports.
"Water levels on the Red River are rising rapidly," the government said on Tuesday in a Facebook post.
Using public loudspeakers commonly used to broadcast Communist propaganda in the past, officials warned residents of the capital's riverside Long Bien district to be on alert for possible flooding, and to be ready to leave the area.
Flood waters have already inundated villages on the outskirts of Hanoi, state broadcaster VTV reported, and authorities were already moving residents from there.
Evacuations were also taking place from flood-prone areas in Bac Giang province, the government said, where the typhoon and floods have caused damage estimated for now to be worth 300 billion dong ($A18 million).
More than 4600 soldiers have been deployed in the province to support the evacuation and support flood victims.
Lao Cai province has reported the highest casualties with 19 people killed and 11 missing, mostly in landslides, according to the disaster management agency.
Floods have also inundated 148,600 hectares or almost seven per cent of rice fields in northern Vietnam and 26,100 hectares of cash crops and damaged nearly 50,000 houses in northern Vietnam, according to the agency.
