A structure fire that engulfed a bronze-casting business in industrial East Billings on Sunday night was likely due to an electrical malfunction, a city fire official said Monday. "There was an electrical failure in a piece of equipment that’s used in their bronzing process," Billings Fire Marshal Mike Spini said after investigating the fire-gutted remains of Billings Bronze Inc. on Monday. "(The investigation) is continuing, but I’m fairly confident it’s an accidental cause. There’s nothing for me to believe that it was intentionally set."