The crash occurred at around 3.30 pm on Road DT716 in Hoa Thang Commune near the Bau Trang tourist area.
According to initial reports, the coach, carrying 16 people, suddenly changed direction before leaving the roadway and falling into the ravine.
Local residents rushed to the scene to pull victims from the wreckage and take them to hospital.
Police and emergency services were deployed to secure the site and investigate the cause of the accident.
Nguyen Duc Hai Tung, Party Secretary of Hoa Thang Commune, was present at the scene, coordinating rescue efforts with authorities.
Four people were confirmed dead, while 10 others were taken to hospital. Rescue teams were deploying cranes to overturn the vehicle and search for two people still missing.
The vehicle was badly deformed, with parts of its bodywork shattered and scattered.