A fire on Acushnet Avenue in Springfield's South End destroyed the building and left 14 residents homeless on June 13.
The fire was reported just before 2 p.m. and there were no known injuries to any occupants.
The building is being considered a total loss.
The second floor was gutted and flames went into the third floor, causing a large portion of the roof to collapse.
Arson investigators believe the fire started in a second-floor bedroom in the rear but the exact cause of the fire is still under investigation.