A transport truck rear-ended a school bus north of Vankleek Hill, Wednesday morning, sending the bus driver and four children to hospital.
It happened around 9 a.m. on Highway 34.
The students are from Pleasant Corners Public School.
OPP said the bus driver was airlifted to hospital in Ottawa, while four children were taken to a local hospital by ambulance.
Police said all had non life-threatening injuries.
Nineteen other children were taken to hospital in another bus as a precaution.