Just after 3:30pm Wednesday afternoon firefighters responded to a school bus fire on Verna Hill and Greenfield Hill Road.  When firefighters arrived they found the rear of the bus on fire where the engine is mounted.  There were about 20 students on board and the bus driver was able to evacuate the students with no problem.  Assistant Fire Chief George Gomola told us the driver went back to investigate the cause of the fire and was overcome with smoke.  He is being treated for smoke inhalation.  No children were exposed any smoke or any or any hazards of combustion.  Gomola said there appeared to be fuel oil or diesel on the roadway and they are investigating if this was a source or contributing factor as the cause of the fire.   About 5 gallons of fuel oil did get in to a nearby stream from water used to battle the fire.  Firefighters used absorbent pads to capture the oil in the stream and notified the Department of Energy and Environmental Protection.