Fire and smoke poured from the B&B Plastics Division Metal-Cladding Inc. plant at 230 South Niagara St. Monday evening, before firefighters could contain the blaze.
Firefighters forced their way into the one-story building and discovered the fire near a plastic tank with combustible materials.
Firefighters were on the scene for more than two hours, but listed the blaze under control at 10:17 p.m. Twenty-three firefighters were called into work.
Fire officials and plant personnel arranged to inspect the plant today in an effort to determine the cause of the blaze and establish the loss.
Firefighters also were called to handle a blaze that caused $9,500 damage at a home at 39 Waterman St., which is owned by David Burbules. The fire rekindled at 1 a.m.