After Chicago police officers shot a man allegedly carrying a gun on Sunday, hundreds of people swept through the city’s streets, injuring officers, smashing store windows, looting and damaging property, police officials said.

More than 100 people were arrested in the unrest, and 13 officers were injured, Chicago Police Superintendent David Brown said during a Monday morning news conference.

“This wasn’t an organized protest, it was an incident of pure criminality,” Brown said. “Criminals took to streets with confidence that there would be no consequences for their actions. I refuse to let these cowardly acts hold our city hostage.”

Mayor Lori Lightfoot echoed that statement Monday morning.

“We are waking up in shock this morning,” Lightfoot said. “This had nothing to do with protected first amendment expression. … This was abject criminal behavior. …This is straight up felony criminal conduct.”

The shooting happened in the afternoon when police responded to a call of a person with a gun in Chicago’s 7th district, according to the Chicago Police Department. Officers said they tried to confront a man who matched the description of the person with the gun when police say the suspect fled and fired a gun toward officers during a foot chase.

The officers fired at the man, striking him, according to police, who said his firearm was recovered on the scene. The man, who police said was a 20-year-old with four previous arrests for burglary, child endangerment, and domestic battery, was brought to a nearby hospital in an unknown condition.

Three officers were also hospitalized for observation, according to police.

The officers involved will be placed on administrative duties, which is department protocol, and the shooting is under investigation, according to police.

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.

Officers who were arresting a man with a cash register were shot at by people passing by in a vehicle, he 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 CPD to 149.

The turmoil led to street closures, notably in Chicago’s Loop, the center of the city’s downtown, according to Chicago’s Office of Emergency Management & Communications.

The looting spread from stores and other businesses in the Loop to several other neighborhoods, including River North, Streeterville, Lincoln Park, the Gold Coast and the South Loop, NBC Chicago reported.

Brown said access to downtown would be “restricted” with a heavy police presence starting at 8 p.m. Monday and lasting until 6 a.m. Tuesday. The department would also monitor outside neighborhoods.

“This is a beautiful city, and CPD will not let criminal act destroy generations of hard work,” Brown said.

CPD Deputy Chief Yolanda Talley had said earlier that misinformation about the age of the man who was shot caused an emotional response from residents.

Talley said the disruptions were “a direct response to one agitator being on the scene, getting people all worked up without having the full story,” NBC Chicago reported. During a news conference, she asked people to “take a step back” to allow a dialogue.

“We want to hear what they have to say” Talley said. “Right now, in this climate, everyone is feeling a certain way about the police, and it’s really unfair to us. It really is.”

Lightfoot was more stern. “To those engaged in criminal behavior — let’s be clear — we are coming for you,” she said Monday morning. “I don’t care what justification is given, there is no justification for criminal behavior.”

“Our citizens deserve to be safe,” she added. “Our officers deserve to be able to do their job without having to worry about shots fired.”

The clashes occurred amid a spike in gun violence in Chicago this year that has hit communities of color particularly hard.

Brown said the weekend saw 31 shootings, including three murders. Nine officers had been shot in the last seven days.