It happened around 3:30 p.m. on the Dalmeny highway near the town.
After the initial collision with the school bus, a pickup truck is reported to have struck the woman’s minivan.
Neither the bus driver nor the 10 children on board were hurt.
A 40-year-old woman and two children who were in pickup truck were taken to RUH by ground ambulance.
An RCMP collision analyst was sent to the scene