WATERBURY, Conn. (AP) Investigators are trying to determine the cause of a fire that swept through an abandoned factory in Waterbury and burned for more than 12 hours.

The blaze at the former Bristol Co. factory began Thursday night and firefighters remained on the scene Friday. The 310,000-square-foot building dates to the 19th century and produced instruments that measured electricity, heat and liquid volume.

Fire Chief David Martin says the fire destroyed the floors in the five-story building and left the walls vulnerable to collapse.

Asbestos may be in the pipes and floor tiling. A 1993 inspection showed the property's soil may contain PCBs, cadmium, chromium, copper and lead. Groundwater also is suspected to be contaminated.

State environmental officials told the Republican-American in Friday that they hadn't been called to the factory site.