The 4-story building, which was connected to a Salvation Army Thrift Store on the southeast corner, collapsed at 10:45 Wednesday morning.
The collapse brought down part of the thrift store and what appears to be converted row homes attached to the back of the building.
Philadelphia Fire Commissioner Lloyd Ayers says as many as eight to ten people were initially trapped in the rubble.
Nine people have been taken to area hospitals so far.
Thomas Jefferson University Hospital says they are treating four victims. Two victims have been taken to Hahnemann University Hospital and three others were transported to the Hospital of the University of Pennsylvania. All five victims are said to be adults. There is no word at this time on the severity of their injuries.
Emergency crews are on the scene continuing to work feverishly to find survivors.
There is no word on exactly what caused the four-story building to collapse.
Commissioner Ayers initially said the collapse happened at an apartment building, but that has turned out to not be the case.
Stay with Action News and 6abc.com as more information becomes available.