ELKHART -- A neighbor used a wooden ladder to get the occupants of a 3rd Street home off the roof as flames grew behind them Monday.Three people were hospitalized, one in serious condition, after the fire broke out at 123 N. 3rd St. Monday around 11 a.m. The occupants of an adjacent residence, also a multi-dwelling unit, were evacuated as the fire breached the building and threatened to spread further, according to Elkhart Fire Chief Chad Carey."It was a pretty intense fire, I could see it from Central Fire Station," he said from in front of the home, as crews blasted a corner of the roof of 119 N. 3rd St. with water from atop an aerial ladder. "Now we're moving into investigation mode."Carey said a passer-by was the first to report the fire, though multiple calls came in. Firefighters responded quickly and had the flames knocked down within the first 10 minutes, he said, and the worst of it was out in about half an hour.At least a half dozen engines and ambulances responded to the blaze. The cause was not immediately known.Carey wasn't sure how many people were helped off the roof before firefighters got there or if they were the same victims who were hospitalized. The most seriously injured victim was transported to a Kalamazoo, Mich., hospital and the other two were taken to local hospitals.Carey credited smoke detectors in the upstairs of the first home and in the neighboring home with alerting residents quickly."We had a quick response and early notification helped too," he said. "The earlier we're notified, the quicker we get there, and that's where smoke detectors are very important."