Other / Not Specified, Other Business Naperville, IL – Sprinkler system keeps early morning fire from spreading in commercial building December 6, 2014 viking210 Firefighters were called to the 2100 block of Corporate Lane about 5:23 a.m. after an alarm was activated and a security guard reported seeing smoke, according to a news release from the fire department. Crews responding to the scene found a hanging heater unit in an engineering room had caused the fire, officials said. However, it was located directly beneath a sprinkler so the fire did not spread.