The crash happened at 19th Street and West Lehigh Avenue around 4:50 p.m.
Police say the 28-year-old male driver of a Volkswagen struck a Nissan, then left the road and hit an 11-year-old boy.
That child was rushed to the hospital and is now in stable condition.
The 52-year-old woman driving the Nissan is hospitalized in critical condition.
The driver of the Volkswagen suffered minor injuries.
L&I was called because one of the vehicles also struck the building at 1915 W. Lehigh.
The circumstances of the crash remain under investigation.