Four people were injured in a collision between a vehicle and a truck Sunday afternoon in Lawrence County. According to police, the vehicle failed to stop at a stop sign on Mt. Herman Church Road in Slippery Rock Township and hit the pickup truck, which was towing a trailer full of Christmas trees. Police say after the collision, the pickup truck rolled on its roof and the trailer traveled about 500 feet down the highway. The vehicle went into a parking lot of a repair shop and hit a school bus that was there to be fixed. According to police, all four people in the vehicle were trapped and were transported to area hospitals. The truck driver was not seriously hurt, but was also hospitalized. Police are investigating.