The crash happened at 8:19 a.m. Wednesday in the area of Torresdale Avenue and Benner Street.
SEPTA says the Route 56 bus was travelling eastbound on Torresdale Avenue when it hit a car, started the chain-reaction.
The view from Chopper 6 showed one car heavily damaged on both the front-end and back-end.
Firefighters and medics were on the scene.
Four passengers on the bus, along with the bus driver, are being treated for non-life-threatening injuries.
There was no word on any injuries to those inside the cars.