THE FLIGHT CREW WAS INFORMED BY THE FLIGHT CREW OF ANOTHER AIRPLANE THAT THERE WAS A TAILPIPE FIRE IN THE NUMBER 2 ENGINE. THE CREW SHUT DOWN THE ENGINE USING THE ENGINE FIRE CHECKLIST; HOWEVER, CRASH FIRE RESCUE PERSONNEL REPORTED THAT SMOKE AND FIRE CONTINUED. THE CAPTAIN ORDERED AN EMERGENCY EVACUATION, DURING WHICH TWO PASSENGERS WERE SERIOUSLY INJURED. EXAMINATION OF THE ENGINE AND SUBSEQUENT TEST CELL RUNNING REVEALED NO ANOMALIES.