The bus and two other cars crashed on the A944, between Aberdeenshire’s Alford and Westhill, at around 4.05pm on Monday.
Police Scotland said the bus was carrying around 20 passengers, all aged between 12 and 16, with the children onboard reporting only minor injuries.
The coach and the Volkswagen Golf involved were travelling towards Aberdeen, while the Volvo was heading towards Alford.
The 39-year-old driver of the VW suffered serious but non-life threatening injuries and was taken to Aberdeen Royal Infirmary for treatment.
The 65-year-old bus driver suffered minor injuries, while the 52-year-old Volvo driver was uninjured.
Sergeant Steve Manson made an appeal for those with dashcam footage to contact police, and said enquiries are ongoing to establish the circumstances around the crash.
Police Scotland said a replacement bus collected the children, and officers have been checking with the local authority to ensure their welfare.