Memphis Police Director Toney Armstrong told reporters that around 9:15 p.m. local time a citizen used the downed officer's radio to report he had been shot multiple times.
Armstrong said the officer was transported in critical condition to hospital, where he was later pronounced dead.
"This is a very difficult time," Armstrong said, adding that it was the third killing of a police officer in the past four years. "It doesn't get any easier."
The suspect remained at large, Armstrong said. He did not release the officer's name, pending family notification.