Schoolchildren were taken to Blackpool Victoria Hospital after a parked car they were in rolled into Claremont park.
The four youngsters, all aged under 11, were in the silver Ford Focus CTEC when the incident happened at around 3.40pm yesterday.
The handbrake was let off, causing the vehicle to roll down a hill from the school car park into the park, off Claremont Road.
The children were treated by the school nurse and ambulances were called, later taking patients to hospital.
Hospital staff were not put on standby for serious or severe casualties.
Headteacher Kirsty Sutton confirmed there had been an incident and ambulances were called as a precautionary measure.
A spokesman for Lancashire Police said: “The children in the car were not badly injured, just shaken up.”