Investigators released images of the two persons of interest who were allegedly seen talking with the victim before the shooting.
Police said the man and the woman could be considered witnesses or potential suspects.
The violence unfolded Monday night in the 300-block of Walker Avenue in Highland Park near the border with Highwood. That's where authorities said a person was shot.
The victim, a 30-year-old man, was transported to a hospital in critical condition, police said. Tuesday morning, police said his condition is improving.
Police said it is an isolated incident and those involved knew each other.
Following the shooting, officers with rifles and shields could be seen patrolling the area along with drones and dogs.
"No I figured they're long gone or they've been down there in the forest preserve, who knows," neighborhood resident Marian McNair said.
McNair was determined to take her morning walk even though police are still looking for two people wanted in connection with a shooting the day before.
"The neighborhood is changing, things change. There was at Santee's a couple of weeks ago and now we don't know the whole story," McNair said.
People living in the area say following the shooting officers armed with rifles and shields could be seen patrolling the area using drones and dogs.
At one point, people were told to shelter in place. Neighbors said the situation was unsettling.
"I don't know. It's starting to get, you know, it's getting pretty nasty. This is something happen in Chicago, Waukegan or North Chicago, but not here in Highwood," one nearby resident said.
Nicola Roberts-Jones said she may have seen the two persons of interest in the neighborhood the day before the shooting,
"It was a similar outfit that's why I recognize a lady, but that was the one thing that kind of made me a little bit more nervous because the fact that you saw them the day before," Roberts-Jones said.
The shelter-in-place has been lifted.
Police are warning the public that if you see either of the individuals, call 911.