The shooting happened Wednesday night in Lower Burrell, a city of about 13,000 residents near downtown Pittsburgh, Westmoreland County spokesman Dan Stevens said. It happened near a Dairy Queen restaurant where the officer's car was parked.
Police at the scene said the other man who died in the gunfire was believed to have been the gunman. Police didn't say whether he was killed by the officer or other officers or shot himself.
"This is still an active crime scene," Stevens told reporters across the street from the restaurant. "This is going to be a pretty extensive scene to evaluate and investigate."
Three hours after the shooting, the officer's body was still in the restaurant parking lot and the other man's body was behind the restaurant near a wooded area and a creek.
Alicia Heymers, co-owner of New Ken Auto-Motive across the street, told the Valley News Dispatch that she was cleaning in her business when she heard a commotion outside. She said she saw several officers with their weapons drawn, firing toward the wooded area behind the restaurant.
"There were a lot of shots, at least six or eight," Heymers said. "I thought (they were shooting at) a bear until I heard them yelling, `Get down, get down!"'