Authorities responded to Whitehall Road and Germantown Pike in East Norriton Township just after 9 p.m. Sunday.
Police said a car hit the pedestrian, then when the person was injured in the street, they were also hit by a tractor-trailer.
Both drivers stopped and remained at the scene.
The driver of the car was believed to be under the influence and taken into custody.
We are working to learn more about the victim's condition.