The five-story building's roof caved in Friday evening, the Chicago Tribune reported.
A preliminary Buildings Department investigation found a contractor doing repairs to the roof moved a heavy load of equipment on one spot on the roof, causing the collapse, department spokesman Bill McCaffrey said.
The Chicago Fire Department ordered the evacuation of 60 residents who lived in the building. Twenty-two of those evacuated will have to find another place to stay, fire department spokesman Juan Hernandez said.
There were no reports of injuries, Hernandez said.
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