It happened around 6:50 a.m. Saturday on the 2300 block of East Lehigh Avenue.
According to authorities, an officer was doing paperwork in the parked car.
The driver of another vehicle then struck the rear of the patrol car.
Police said the officer hit the windshield during the impact and was taken to the hospital for treatment of non-life-threatening injuries.
The female driver of the striking vehicle was said to be cooperating with police.