Local authorities said 56-year-old Nguyen Hoang Que in Nghi Thiet commune, Nghi Loc district, died of electrical shock after heavy rain and strong wind broke power lines near his house.
Meanwhile, Nguyen Trung Hai, born 1966 and Le Thi Ngoan, 1995, were swept away by flood and remained unaccounted for.
The dreadful weather also caused the collapse of a house in Nghi Loc district and submerged nearly 2,000 hectares of corn fields and vegetables as well as 874 hectares of fishery farms.
Various local roads were said to be flooded, with thousands of students told to stay home on the day for safety reasons.
All schools in nearby Ha Tinh province also had to temporarily close on October 10.
The National Centre for Hydro-meteorological Forecasting has predicted rainfall of between 100 and 250 mm for coastal central provinces from Thanh Hoa to Quang Ngai from 1am on October 10 to 7pm on October 11.
This was attributed to the impact of a tropical low-pressure system, which has weakened and is moving west-northwest at 25km per hour.