CHICAGO (CBS) — The search continued Tuesday for a gunman who shot a man at the State Street Bridge during the afternoon rush on Monday.

Police said they don’t believe it was a random shooting. The victim was on his way to work Monday afternoon when he was shot in the head.

Chicago Police Cmdr. Gary Yamashiroya said the victim was heading to work, northbound on the bridge, when a male subject approached him, pulled out a weapon and shot him in the head.

CBS 2’s Suzanne Le Mignot spoke with the 29-year-old man’s wife on Tuesday. She said her husband was resting at Northwestern Memorial Hospital and trying to recover. Miraculously, the bullet did not enter his skull.

The victim’s wife also said police don’t yet know the motive for the shooting.

The incident happened at the height of the evening rush hour, as people were heading home in the train. Witnesses heard a gunshot, and saw a man fall to the ground, covered in blood.

“Two men were together – I thought they were together – and all we see is just one man took out his gun and shoot him in the back of the head,” said witness Sameisio Lewis.

Lewis told WBBM Newsradio that it appeared the shooter pulled the trigger after a brief conversation with the victim.

The gunman remained at large on Tuesday and a Chicago police detective was at the scene of the shooting Tuesday morning.

Kristen Phelan-Swiderski, who works near the shooting scene, said the detective spent time questioning people who frequent the State Street bridge area.

“I was walking past and he was asking some general questions to gentlemen who happened to be sitting on the bridge, who I know happen to sit there a lot,” she said. “And he was just asking them, ‘Have you seen him’ and, I guess they had some information that they saw him going on Lower Wacker.”

Witnesses said the gunman ran south on State Street, then east on Wacker Drive after the shooting.

Phelan-Swiderski also said the detective was showing people either a photo or sharing a description of the suspect.

There are several surveillance cameras near the shooting scene. Detectives typically request any and all city surveillance camera footage to help in their investigation.

Among the cameras that might have captured something was a camera at State and Wacker that is part of Operation Virtual Shield – an extensive network of surveillance cameras found throughout the city.

“I hope they find him,” Phelan-Swiderski said.

Shawn Bunch, who witnessed the aftermath of the shooting said, “Yesterday should be a lesson in the history books of Chicago – that no place is invincible. No place is separate. Everything needs to be treated exactly the same, be it the West Side, South Side, East Side, North Side or downtown Chicago, because we’re all under the same umbrella.”

The suspect is described as a black man about 6 feet tall with a short afro and a skinny build. He was wearing a light blue dress shirt with the sleeves rolled up and black shorts, and was holding a chrome-colored handgun, police said. He might have been wearing a raincoat.