The accident in the Mekong Delta province occurred at around 10 a.m. at the construction site of a garment factory in the Hoa Phu Industrial Zone, Long Ho District. Dozens of workers were trapped under the rubble when the wall crumbled.
Rescue forces, including police personnel, were dispatched to the accident site. It took them more than an hour to get the victims out.
At around 11 a.m., the bodies of five workers had been taken out and four others were taken to the local hospital for emergency treatment. One of them died later, local authorities confirmed Friday afternoon.
Rescue forces are still looking for missing workers, they said.
An investigation had been launched to establish the cause of the incident.
Construction site accidents are not uncommon in Vietnam. Last year, three workers were killed when a landslide hit a construction site in the northern province of Lao Cai.