The fire started on the roof of the building just after 3 p.m. on Monday, Sept. 12, the outlet reports citing Deputy Fire Chief Adam Roche.
Heavy smoke was seen coming from the five-story building, located at 299 Highland Street, all across the city.
The worker's injuries were said to be non-life threatening, according to Roche, and it took about 30 minutes to contain the fire. No other injuries were reported.
People were being told to avoid the area between Highland Street and Newton Square as crews addressed the fire, the City of Worcester said on Twitter.
Roche said crews were putting insulation on the roof when the fire started, but it is unknown whether or not that was the exact cause. The investigation is ongoing.
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