A member of the Planet Fitness gym was outside the building and noticed the fire in the alleyway between the Tumble Gym and the former Schrier Brothers Paper Co.
When firefighters arrived, the flames were getting closer to the building. The first responders cut a lock on the gate into the alley and began to quickly extinguish the fire.
Fairfield police, who were on the scene assisting with security, found that a worker had been welding in the area. According to the fire department report, employees of CT Dismantling had been working in the area and using torches to cut and remove steel pipes near where the fire began.
Metal slag, consistent with welding debris, was found in the area, firefighters said.
It took less than an hour to put out the blaze, firefighters said. No fire extended into the surrounding buildings, and the fire department left the scene at 10:40 p.m.
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