Bualoi had moved along Vietnam's northern central coastline before making landfall early on Monday, causing waves as high as eight metres, according to the national weather agency.
One person died after being caught in floodwater in Hue city, and another was killed by a falling tree in Thanh Hoa province, the government's disaster management agency said.
Seventeen fishermen were missing after huge waves hit two fishing boats off Quang Tri province, while another fishing boat lost contact during the storm, according to the agency.
"I've witnessed many storms, and this is one of the strongest," said 45-year-old Nguyen Tuan Vinh in Nghe An province as he was cleaning up debris.
Vinh's neighbours said they stayed up all night trying to protect their homes, even as the power to their apartment building went down.
"I stayed awake the whole night fearing the door would be pulled off by strong winds," said resident Ho Van Quynh.
By 2pm AEST, the typhoon was moving over Nghe An province into Laos, with maximum wind speeds weakening to 74km/h from 117km/h when it made landfall, the weather agency said.
Bualoi has so far damaged 245 houses, inundated nearly 1400 hectares of rice and other crops, and cut off access to several areas, the disaster management agency said in a report.
No major damage to industrial properties was mentioned in the report, though there are some large factories in or near Bualoi's path, including those owned by Foxconn, Luxshare, Formosa Plastics and Vinfast.
Ahead of the typhoon hitting, the government had evacuated more than 28,500 people, while hundreds of flights were cancelled or delayed as four airports in central provinces were closed.
The cyclone has triggered heavy rains across most of Vietnam since Saturday, and authorities have warned of the risk of severe floods and landslides.
Rainfall in several parts of Vietnam was forecast to hit 500mm from Sunday night through Tuesday, according to the weather agency.Â
With a long coastline facing the South China Sea, Vietnam is prone to typhoons that are often formed east of the Philippines, where at least 10 people died after Bualoi hit there last week.
with Reuters
