Hagupit made landfall in Vietnam on Wednesday, triggering severe flooding and landslides in eight mountainous provinces, said the national flood and storm control committee.
More than 60 people have been injured, several thousand homes have been inundated with floodwaters and thousands of hectares of crops have been destroyed.
Material losses have been estimated at more than one trillion dong (60 million dollars), the Hanoi-based committee said.
Government staff and soldiers are trying to distribute relief supplies to survivors in remote and mountainous areas, who were cut off from the outside world for several days.
Floods and storms in Vietnam claim hundreds of lives every year between July and November.