Overheated oil ignited Sunday morning at a 100 Maynard St. industrial plant, where city firefighters prevented any significant damage.
Mineral oil used to create coiled metal wire overheated at the Williamsport Wire Rope Co., said city fire department acting platoon Chief Sam Aungst.
"There was a wire strander machine left on during non-working hours," Aungst said. "The thermostat controlling the temperature malfunctioned and the lubricating oil caught fire."
No one was working when a manager conducting a building walk-through noticed the ignited oil and called for assistance around 7:30 a.m., according to John Miller, rope company security guard.
Flames were extinguished within an hour, firefighters reported to emergency radio dispatchers.
Besides the contained oil, Aungst said there was no damage.
Smoke was successfully ventilated from the structure, which is the former home of the Bethlehem Wire Rope Co.
Employees should be able to return to work today, according to Aungst.