The feared typhoon Rammasun landed in the northern province of Quang Ninh on Saturday morning and weakened to a tropical depression by the afternoon, with no deaths and only minor damage reported.
Mong Cai was the first destination in Vietnam to be hit by winds of 89 to 117kph as the typhoon moved out of China, where at least eight people were killed.
Blackouts were reported across the town starting at 7:45am.
An update from the National Center for Hydrometereological Forecasting at 2:30pm said the typhoon had thoroughly diminished above Cao Bang and Lang Son Provinces in the northeast highlands.
Cao Duc Phat, minister of agriculture, said the typhoon had slowed to winds of between 40-60 kph.
The typhoon had raised concerns during its approach, spitting winds of up to some 180kph as it built strength in an unusually warm Gulf of Tonkin. The storm was categorized as a super typhoon in China, a term that describes storms carrying winds of 250kph or higher. Casualties caused by the typhoon rose to 77 in the Philippines.
Nguyen Xuan Ky, the head of the Mong Cai Party Unit, said he has not been informed of any casualties in town.
More than 200,000 people in Quang Ninh and nearby localities were evacuated to local border guard stations and elsewhere by the time it arrived.
The roofs of 19 small houses were blown off, three electric poles and dozens of street trees were felled, when the typhoon had reached 70 kilometers inland.
Phat said the town was well-prepared for the storm and the damage was not significant.
Le Thanh Hai, deputy director of the National Center for Hydrometeorological Forecasting, said additional rainfall of around 300mm would follow the passing of the storm.
Some areas have been warned to brace for flash floods and landslides.
“Many storms caused no initial casualties at sea or along the coast, but many people were subsequently killed by landslides and flash floods. We need to move people immediately from risky areas,” Phat told Tien Phong.
The country's three air carriers, Vietnam Airlines VietJetAir and Jetstar Pacific all cancelled and delayed domestic flights, on Saturday, coming to and from Hai Phong, which neighbors Quang Ninh Province.