Waterbury Fire was dispatched to 125 Hillside Ave for a possible structure fire. First due Engine 6 reported they had a large wood boarded up vacant structure with heavy smoke showing. As they worked to open up the building and secure a water supply the ladder companies set up to take the roof. Crews pushed into the structure to gain access to the attic space where the fire appeared to be seated. They would have their work cut out for them chasing fire in the walls and attic space of the top floor. The ladder companies opened up the roof to assist in ventilating the structure as the interior crews pulled the ceilings and opened the walls. The main body of fire was knocked down within about 40 minutes but an extended overhauling operation would be required to get all the hot spots extinguished. The City's Fire Marshal was on scene and the investigation into the cause of the fire was begun as companies started picking up.