Authorities are investigating a fire that they say was intentionally set late Wednesday night at a former mental facility, which is currently being used for a holiday light display in Waltham.
Crews responding to a reported fire at the former Walter E. Fernald Developmental Center’s administration building on Trapelo Road just before midnight found flames coming from the back of the building.
One firefighter suffered a minor injury and was treated at the scene before returning to duty, according to Waltham Deputy Fire Chief Roger Hebert.
The fire was intentionally set, causing extensive damage to the basement of the building, Waltham Fire Chief Thomas MacInnis, Waltham Police Chief Keith D. MacPherson, and State Fire Marshal Peter J. Ostroskey said in a joint press release.