Vietnamese state broadcaster VTV said the torrent of water gushing down from a mountain in Lao Cai province Tuesday buried Lang Nu hamlet with 35 families in mud and debris.
Only about a dozen are known so far to have survived. Rescuers have recovered 30 bodies and are continuing the search for about 65 others.
The death toll from Typhoon Yagi and its aftermath has climbed to 155. Another 141 people are missing and hundreds were injured, VTV said.
Floods and landslides have caused most of the deaths, many of which have come in the northwestern Lao Cai province, bordering China, where Lang Nu is located. Lao Cai province is also home to the popular trekking destination of Sapa.