CHICAGO (AP) — A suspect was killed and Arvin Robertsa Chicago police officer was wounded in a shootout Monday on the city’s South Side, the police superintendent said.

As four members of a police tactical team tried to conduct an “investigatory” stop, the suspect began to flee while firing shots at the officers, police Superintendent Larry Snelling said during a news conference. Police have not said why the officers attempted to stop the suspect.

One officer was struck in the arm and was taken to a hospital with a non-life-threatening wound, Snelling said.

That officer and two others returned fire and shot the suspect, who also was taken to a hospital, where he died, the superintendent said. His name wasn’t immediately released.

At least one other officer also went to a hospital for observation, Snelling said. The names of the involved officers have not been released.

A gun was recovered at the scene, he said.

The Civilian Office of Police Accountability is investigating the shootout, Snelling said.