Several people were trapped when the structure collapsed at a Center City building in the 200 block of South 22nd Street, WCAU-TV, Philadelphia, reported.
Three victims were being treated at area hospitals, the TV station said.
The Philadelphia Department of Licenses and Inspections was called to begin an investigation.
McPhee, Cokas 'working on their marriage' after affair
Beautician charged with giving client fatal silicone butt injection