PA28 instructor pilot experiences an engine fire while attempting to start the engine after a brief stop. The instructor and students evacuate and an airport worker arrives with a fire extinguisher and puts out the fire.

Narrative

My students and I were on a training flight to an uncontrolled airport; where one of my students was practicing touch and go's. After 0.9 hours of flight we landed; parked the airplane and shut it down. I then had my students switch seats from the back to the pilot seat so the other student could fly. Upon start-up we attempted to use the hot engine start checklist. The airplane did not start. We waited and then attempted to start the engine using the normal start checklist; and we primed 3 times; I did this because I thought the engine did not start due to fuel starvation. We then noticed flames coming from the engine compartment; we kept cranking for only a second or two and set the mixture lean; fuel pump off; fuel selector off; I told my students to exit the plane and turned off the ignition. I then attempted to extinguish the fire with the airplanes fire extinguisher which did not put the fire out. Then a worker at the airport brought over a larger fire extinguisher and we then put the fire out. I notified my flight school and asked them to contact the Fire Department.