Authorities say more than 100 people were arrested and 13 officers were injured following a night of unrest and looting in downtown Chicago.
On Sunday afternoon, an officer-involved shooting took place in the city's Englewood neighbourhood.
Hundreds of people swept through streets of Chicago overnight, injuring police officers, smashing store windows, looting and damaging property after police officers shot a man they say was armed, officials said.
More than 100 people were arrested, and 13 officers were injured, Chicago Police Superintendent David Brown said Monday morning at a news conference.
"This wasn't an organised protest. It was an incident of pure criminality," Nbcnews quoted Brown to have said. "Criminals took to streets with a confidence that there would be no consequences for their actions. I refuse to let these cowardly acts hold our city hostage."
Mayor Lori Lightfoot also called the actions criminal.
"We are waking up in shock this morning," Lightfoot said Monday. "This had nothing to do with protected First Amendment expression. ... This was abject criminal behaviour. ...This is straight-up felony criminal conduct."
The shooting happened Sunday afternoon when police responded to a call of a person with a gun, according to the city's police department.
Officers said they tried to confront a man who matched the description of the suspect when he fled on foot, firing toward officers as he did.
Two officers fired back, striking the man, identified as a 20-year-old with four arrests for burglary, child endangerment and domestic battery. He was taken to a hospital, where he was in stable condition, according to the Civilian Office of Police Accountability, which is investigating the shooting.
Police said a firearm was recovered at the scene and three officers involved were hospitalised for observation.
The officers involved will be placed on administrative duties, which is department protocol.
Brown said "tempers flared, fueled by misinformation" about the shooting. Police started noticing social media posts encouraging looting and were then called to reports of a mob scene at about 12:20 a.m., he said.
The injured officers included a sergeant who was struck with a bottle and another whose nose was broken, Brown said. Details about specific injuries to other officers were still being gathered, said Thomas Ahern, the Deputy Director of News Affairs and Communications for the Chicago Police Department.
Officers who were arresting a man with a cash register were shot at by people passing by in a vehicle, Brown said. A security guard and a civilian were struck by gunfire during the early morning hours and taken to hospitals.
Five guns were recovered during the unrest, Brown said, bringing the total of weekend guns recovered by police to 149.
The turmoil led to street closures, notably in Chicago's Loop, the centre of the city's downtown, according to Chicago's Office of Emergency Management and Communications.