Two Ornge helicopters, one from Toronto and one from London, transported the injured to hospital.
One patient was flown to Sunnybrook Hospital in critical condition.
Ornge is transporting the other patient to either Sunnybrook Hospital or St Michael's Hospital.
The injured child is going to Sunnybrook pediatric.
The collision happened in New Tecumseth.
Roadways around the collision were closed for police investigation.