More than 170 firefighters were battling the blaze Wednesday when the roof collapsed. Officials say the vacant building was more than 50 years old. Chicago Fire Department officials say five firefighters remain hospitalized after a blaze that left two dead and 17 injured. Fire officials say the five are in good to stable condition and are expected to be released soon. Fire Commissioner Robert Hoff says preliminary evidence suggests the fire was not the cause of the roof’s collapse. He says fire appeared to have been contained to an office at the back of the building. There’s no word on the cause of the fire. Firefighters say they treated the blaze carefully in case squatters had started the fire and were trapped inside. Hoff says no one was found.