Apartment Building, Residential Late night apartment fire extinguished by sprinkler system (Tucson, AZ) August 27, 2012 viking210 Firefighters entered the apartment to find the fire had already been extinguished by a single sprinkler head. The initial cause of the fire was a pan of oil left unattended on the stove. Due to the quickness of the alarm sounding and the efficiency of the sprinkler system, damage was kept to a minimum, and there were no injuries to report.