As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB AT APPROXIMATELY 1000 AGL THE LOWER AFT CARGO FIRE WARNING LIGHT AND BELL CAME ON. AN EMERGENCY WAS DECLARED AIRCRAFT RETURNED TO AIRPORT AND LANDED WITHOUT INCIDENT. POST FLIGHT INSPECTION FOUND LOWER AFT CARGO COMPARTMENT WITH BOXES STACKED TO THE CEILING AND IN VERY CLOSE PROXIMITY OF THE SMOKE DETECTORS. ADJUSTED LOAD, AND PERFORMED SYSTEM CHECK OF FIRE/SMOKE DETECTION SYSTEM NO DEFECTS NOTED. AIRCRAFT WAS RETURNED TO SERVICE.