B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 460
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Evacuated
Aircraft
During deplaning; APU was still powering airplane electrical and air.  Ground power was available but not yet in use.  APU power dropped off airplane and an APU Fault light was observed.  Ground power was selected.  A momentary APU fire light illuminated; but extinguished by itself.  APU was turned off.After a moment or two; APU Fire illuminated again with warning bell.  Bell was silenced; and fire handle was pulled.  Fire light remained illuminated.  APU fire extinguisher was then discharged.  Fire light then went out.We contacted ATC via VHF radio and requested fire equipment.  We also directed all remaining passengers to leave their carry-ons and exit quickly through door to Jetway.
B737 Captain reported an APU fire warning during deplaning.