What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Narrative: while passengers were being loaded, it was noticed that the APU had smoke and flames coming out of the tailpipe. The flight crew shut down the APU which shut off the lighting in the cabin. The APU was pumping smoke into the cabin so the flight attendant declared an emergency and evacuated the aircraft. The L-2 door slide was deployed and approximately 20 passengers evacuated without incident or injury. This incident is closed.
As the FAA filed it
NARRATIVE: WHILE PASSENGERS WERE BEING LOADED, IT WAS NOTICED THAT THE APU HAD SMOKE AND FLAMES COMING OUT OF THE TAILPIPE. THE FLIGHT CREW SHUT DOWN THE APU WHICH SHUT OFF THE LIGHTING IN THE CABIN. THE APU WAS PUMPING SMOKE INTO THE CABIN SO THE FLIGHT ATTENDANT DECLARED AN EMERGENCY AND EVACUATED THE AIRCRAFT. THE L-2 DOOR SLIDE WAS DEPLOYED AND APPROXIMATELY 20 PASSENGERS EVACUATED WITHOUT INCIDENT OR INJURY. THIS INCIDENT IS CLOSED.