Apartment Building, Residential Rochester, MN – Officials credit sprinkler system with saving apartment building February 9, 2015 viking210 Officials believe a sprinkler system in an apartment building “definitely saved” the complex from more serious damage after a fire late Saturday. A general flow alarm — which indicates the sprinkler system has been activated — came in about 10:40 p.m. Firefighters responded to 875 21st Ave. SE, where they found there had been an active fire in one of the apartments on the third floor. They found a frying pan with oil in it, unattended on the stove, said Larry Mueller, assistant fire marshal. The initial flare-up triggered the overhead sprinkler, which eventually extinguished the flames.