Two children have been rushed to hospital with serious injuries after being hit by vehicles in separate collisions on Friday afternoon.

It is understood a child had just left the Cooloongup Primary School when they were hit by a car at 3.05pm on the corner of Willmott and Grange drive.

Emergency services rushed to the scene, with a St John ambulance taking the injured child to Rockingham Hospital under lights and sirens.

The condition of the child is unknown.

Another child was riding a scooter on Harborne Street, near the intersection of Leeder Street, in Glendalough when they were struck by a bus around 4.35pm.

The kid was rushed by St John ambulance under lights and sirens to Royal Perth Hospital.

The child has serious injuries.