It crash occurred just after 4:30 p.m. at 19th Street and Cecil B Moore Avenue.
Officers were responding to an assist call when a police vehicle struck two pedestrians, then collided with a civilian vehicle.
One of the pedestrians, a 33-year-old woman, was trapped in the wreckage for about 15 minutes before she was freed.
She was taken to Temple University Hospital with serious injuries.
The other pedestrian, the woman's husband, refused hospitalization.
No other injuries were reported.
The names of the victims have not yet been released.
