The bus, one of three carrying local government officials on a field trip, veered off the road in Prachin Buri province, east of Bangkok. Of the 49 people onboard, 17 were confirmed dead at the scene, and one more succumbed to injuries in the hospital, said Police Lieutenant Colonel Siwapass Phuripatchaiboonchu.
The driver told authorities that the brakes failed as the bus descended the hill, causing the crash. Survivors were taken to two local hospitals for treatment.
Thailand's road safety record is among the worst globally, with the World Health Organization reporting around 20,000 fatalities annually. Unsafe vehicles and poor driving are key contributors to the country's high road toll.
In October, a school bus crash in a Bangkok suburb killed 23 people, including many children, marking Thailand’s deadliest road accident in a decade.