A school district and a business that provides school bus transportation said Friday they are removing the district’s propane-fueled buses from service

 A school district and a business that provides school bus transportation said Friday they are removing the district’s propane-fueled buses from service out of an abundance of caution as the state Fire Marshal’s Office investigates what led to an explosion and fire that critically injured two bus company workers. The two men who suffered serious burns were performing a state-required inspection on a propane-powered bus at at the Student Transportation of America building in Bradford on Thursday. They were the only people in the building at the time. The cause of the explosion has not been determined. The district said it has about 20 large buses used for daily transportation, plus several smaller buses. Six of the 20 large buses use propane, and are now off-line. The District and company met throughout the weekend to coordinate a plan to ensure all students will be safely transported to school on Monday morning when they return from winter break.