Highland Park residents were asked to avoid the area of the 300-block of Walker Avenue, near the border with Highwood, the city said.
Residents in the area were told not to open doors or windows to unexpected visitors, and to call 911 with any concerns.
An injured person was being taken to a local hospital.
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The person's condition was not immediately known. Police have not released details about the circumstances surrounding the shooting.
Highland Park police are looking for two people, a man and woman, seen talking with the victim before the shooting.
Police used dogs and drones to assist in a search, officials said.
Officers with rifles and shields were seen patrolling the area as authorities continued their response.
Just after 10:30 p.m., officials lifted the shelter-in-place.
They said the suspects have likely left the area.
Neighbors described the situation as 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.
Anyone with information is asked to call 911.