Quinton Frierson, aka "Ferguson," 27, fom the 5600 Block of Carpenter Street, is charged with murder.
Police say Frierson got into an argument with the victim, 20-year-old Victor Rodriguez of the 900 Block of E. Schiller Street and shot him once in the head.
An off-duty Chester police officer happened to be at the scene near the Crown Fried Chicken restaurant at South 52nd and Locust streets.
That officer fired at the gunman but missed. He did manage to take the gunman into custody.
Police say the gun used in the crime was recovered at the scene.