Police say the officer was shot in the shoulder while chasing a man down Mather Street in the city's north east section just after midnight. Police had been called to the area to investigate a report of a man with a gun.
The officer, whose name has not been released, was taken to Saint Francis Hospital and was in stable condition Saturday afternoon.
Police recovered a rifle they believe was used in the shooting, and a suspect surrendered a short time later.
That man was being questioned Saturday and was expected to face several criminal charges.