A mechanic was sawing steel to repair the Quang Lợi Appliance Supermarket in Đức Nhuận Commune when a spark set flammable materials nearby on fire.
The fire spread quickly to four other buildings in the area.
Hundreds of firefighters and many fire engines were dispatched to the scene, and the blaze was under control two and a half hours later.
No loss of human life was reported, but hundreds of appliances in the store were destroyed.
The case is still under investigation.
