The woman was found lying in the roadway on I-95 southbound, at mile marker 19.1, near the Walt Whitman Bridge / Packer Avenue Exit around 10:30 p.m.
When officers arrived, they discovered the incident was two separate crashes.
The initial incident was a single vehicle crash. Police say they driver of a red Chrysler 300C lost control of the car and crashed into the median multiple times, disabling her vehicle in the left lane.
Officials say the driver got out of the car and was struck by another vehicle.
That second vehicle did not stop and continued down I-95 SB, according to police.
Pennsylvania State Police, as well as PennDOT, arrived on scene and shut down the highway.
The woman was taken to Jefferson Hospital in critical condition.
Anyone with information on this incident is urged to contact the Pennsylvania State Police, Criminal Investigation Unit, 215-452-5216.