The shootings occurred late Monday night about a block from the police department's 4th Precinct, where protesters have been demonstrating since the shooting of 24-year-old Jamar Clark on Nov. 15.
Police Department Spokesman John Elder said in a news release that officers responded to the sound of gunshots around 10:40 p.m. and 911 calls shortly after reported five people had been shot. Dozens of officers assisted victims and secure the scene, the statement said.
Elder said three victims were taken to a hospital in a private vehicle, and two were transported by ambulance. All had injuries that were not life-threatening. Mica Grimm, an organizer with Black Lives Matter who said she arrived on the scene soon after the shooting, said two of the wounded were hit in the leg, another in the arm and a fourth in the stomach.
It wasn't immediately clear what prompted the shooting or how many suspects police were searching for. No one was in custody, and police are interviewing witnesses and ask that anyone with information come forward, the statement said.
Oluchi Omeoga, who has been participating in protests since last Monday, witnessed the incident.
Protesters saw three people wearing masks who "weren't supposed to be there," Omeoga said. Eventually, the three people left the crowd and began walking down the street, and a few protesters followed. When they reached a corner, the three people pulled out weapons and gunshots rang out, Omeoga said.
The scene early Tuesday was quiet, with about 200 people milling around and talking. Campfires were lit for warmth amid freezing temperatures. One man with a bullhorn led protesters in chants of "Jamar Clark!"
Clark's family, in a statement attributed to his brother Eddie Sutton and issued through U.S. Rep. Keith Ellison's office, thanked protesters for "the incredible support" they have shown the family.
"But in light of tonight's shootings, the family feels out of imminent concern for the safety of the occupiers, we must get the occupation of the 4th precinct ended and onto the next step," the statement said.
Black Lives Matter had previously planned to announce "next steps" on Tuesday morning following a weekend meeting with community members about strategy.
Authorities have said Clark was shot during a struggle with police after he interfered with paramedics who were trying to assist an assault victim. But some people who said they saw the shooting allege Clark was handcuffed.
Protesters and Clark's family have been calling for investigators to release video of the shooting. The state Bureau of Criminal Apprehension said it has video from the ambulance, a mobile police camera and other sources, but none of it shows the event in its entirety. The agency, which is conducting a state investigation, said releasing the footage now would taint its investigation.
A federal criminal civil rights investigation is also underway to determine whether police intentionally violated Clark's civil rights through excessive force.
Associated Press writer Sarah Rankin in Chicago contributed to this report.