"We don't believe this is a random act. We think that this was an instance where the person was specifically targeted," said Chicago Police Commander Gary Yamashiroya. "We are still determining if they know each other."
Police said the gunman walked up behind his 29-year-old victim and fired one shot into the back of the man's head at 5 p.m. The man was on his way to work, walking across the State Street Bridge near Wacker Drive and State Street when he was shot. Officials are still searching for the gunman, who fled on foot, southbound down State Street.
The victim was taken to Northwestern Memorial Hospital in critical condition, but appears to have suffered only a graze wound.
"We're still determining the motive," said a Chicago Police Department commander. "We have a detective at the hospital. He appears to be talking to the detective."
Detectives are also talking to witnesses reviewing surveillance videos.
"I just heard a noise, it was like a car backfiring. I looked outside the window and I saw a gentleman running southbound on State Street in a white t-shirt. And another one on the phone. And then somebody said, 'somebody's shot,'" Gary Reidy said.
"I heard a boom, like a gun sound. As we wall, all you can see is the man fall and the other man took off, over there," said Samleiso Lewis.
The State Street Bridge and nearby streets were blocked off by police during the investigation. Several CTA buses were also rerouted around the scene.