An officer and a suspect traded shots Sunday after the officer saw the suspect firing at a 39-year old man, St. Louis police said. The officer was one of two who were traveling at 2:20 p.m. west in a police vehicle on the 5900 block of Lucille Avenue when they saw the shooting. One of the officers fired shots at the suspect, a 37-year old man. He was not hit. The suspect turned and fired a shot at the officer, which also missed. The suspect ran through a gangway and out of sight. The victim was shot in the thigh and was in stable condition at a hospital. He and the suspect, who know each other, had been involved in a dispute, police said. The suspect was arrested later at a residence in the 4900 block of Lilburn Avenue.