The officer was responding to a call around 12:30 a.m. on Thursday when the officer's marked patrol car collided with a GMC SUV at 5th and Callowhill streets in Philadelphia's Spring Garden section.
Both vehicles ended up on the sidewalk.
Police say the 34-year-old officer was knocked unconscious, and is being treated for head and face injuries.
Two teenage males and a woman in her 20s, who were all in the SUV, are being treated for cuts.
Police are checking to see if the officer had activated the lights and siren on the patrol car.
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