Police said the 29-seat vehicle crashed into a stretch of guardrail for about 50 meters before flipping over on a sloped road connecting National Highway 32 and Provincial Road 174 in Mu Thap Hamlet, Yen Bai Province.
The group was traveling to the Ta Ghenh village school site under Hoa Mi Kindergarten for volunteer work when the accident happened. Rescuers brought the victims out of the vehicle and rushed the injured to nearby medical facilities. The bus was heavily damaged, overturned with debris scattered around.
Initial findings suggest the vehicle suffered brake failure while descending.