Eight passengers and both of the vehicles' drivers were killed in the accident, which occurred early Monday morning in Binh Thuan province's Ham Minh village, said Le Vinh Chi, the village's chief.
The passengers who were killed were in the smaller 24-seat bus, which was bound for the southern hub of Ho Chi Minh City, Chi said.
The cause of the accident was under investigation. Nearly 9,000 people were killed in traffic accidents last year in Vietnam despite tougher measures by the government to curb fatalities, including stricter oversight of vehicle overloading and improvement of infrastructure.