The incident occurred at 7 am at a 70-metre-long and eight-metre-wide section along the river, causing parts of ten houses in Binh Thuy District to fall into the river.
Resident Le Thi Nam said she started to hear some sounds and see long cracks on the floor at 6 am.
"Our kitchen and toilet, which lies near the river bank, fell into the river within 30 minutes," she said. "We're now moving our furniture out in case more parts of the house are affected."
Binh Thuy authorities have sent a rescue team to the site to deal with the erosion and help evacuate households to safety.
Nguyen Van Cong, Deputy Head of the Binh Thuy District Steering Committee for Natural Disaster Prevention and Control and Search and Rescue, said they also warned local people about possible erosion in the coming months.
Binh Thuy River has faced erosion over the past few years.
The committee has proposed the construction of a dyke system along the Binh Thuy River banks to prevent erosion.
