The incident was reported just before 2:30 p.m. Wednesday in the 1400 block of West Tioga Street.
Firefighters were called out for a partial collapse of the rear of a vacant building.
Five families in an adjacent building had to be evacuated as a precaution.
The Philadelphia Licenses and Inspections Department is on scene.
The Red Cross said it is helping a family of three at the Red Cross House. The other four families have made other plans.