A Slippery Rock School District bus waits on Route 173 in Brady Township on Tuesday after is was involved in a chain-reaction collision at about 4 p.m. Six students were on their way home when their bus was rear-ended. State police said the children and drivers were checked out by emergency medical personnel, but no one was taken to the hospital. The bus and one of the cars were stopped on the road and a third vehicle crashed into the car, pushing it into the bus. There was no police report available.