The accident happened near an intersection at Ban Nonghor in Tambon Mae Chan of Mae Chan district.
The Students and teachers are from Serm Ngarm school in Serm Ngarm district of Lampang and were on an educational tour to Chiang Rai on a chartered bus from Chiang Mai.
The driver, identified as Manas Mooneye said the buses brakes failed at the intersection on Phaholyothin road, to avoid ramming into the stopped cars, he swerved to the right immediately causing the bus to flip and crash into a mini van on the opposite side of the road.
25 students and including the driver were injured, two seriously, nine Year old Wadikan Chuajedton sadly succumbed to her injuries.
The driver was detained for reckless driving, police said.