CHICAGO – Hundreds of people swept through the Magnificent Mile and other parts of downtown Chicago early Monday, smashing windows, looting stores, confronting police and at one point exchanging gunfire with officers, authorities said.


More than 100 people were arrested as of 9 a.m., according to Chicago Police Superintendent David Brown. Thirteen officers were injured during the unrest, including a sergeant who was hit by a bottle. A civilian and private security guard were shot and wounded.


"What occurred in our downtown and surrounding communities was abject criminal behavior, pure and simple," Mayor Lori Lightfoot said. "And there cannot be any excuse for it. Period."


It took police officers roughly four hours to get the downtown back under control, leading to finger-pointing across the political spectrum and calls for the Illinois National Guard to once again help quell unrest in the country's third-largest city.


Downtown Alderman Brian Hopkins, who said he was on Michigan Avenue from midnight to 4 a.m., described a scene in which officers were overwhelmed by looters and apparently did not have much of a plan for restoring order. He criticized Lightfoot for failing to develop an effective strategy following looting incidents in May and June.


"The real question today is, where was the strategy? What was the decision-making at the highest levels?" Hopkins said. "That means the police superintendent and the mayor, who's a very hands-on mayor when it comes to these kinds of decisions."


City officials said the seeds for the violent crime spree were sown on social media Sunday afternoon following an officer involved shooting in the Englewood neighborhood. Officers shot and wounded a 20-year-old man Sunday after he fired shots at them while being chased, authorities said.


The man was taken to University of Chicago Medical Center and is expected to survive, Brown said.


The Civilian Office Police Accountability, the city agency that investigates all officer-involved shootings, released a statement confirming Brown's assertion that the wounded male is an adult. Some social media accounts that authorities say fueled the unrest referred to him as a 15-year-old boy.


More than an hour after the shooting, police and witnesses said a crowd of about 30 people faced off against officers holding a police line near 56th and Aberdeen streets. During a scuffle, one officer was hit with pepper spray and a second officer suffered a minor shoulder injury.


Two people were arrested and a police car window was shattered by a brick, police added.


A large number of officers cordoned off streets in nearly every direction until the mood of the crowd cooled off. But by that time, Brown said, messages began appearing on social media encouraging people to head downtown.


The looting and vandalism began shortly after, with people streaming in and out of high-end stores. Some could be seen throwing merchandise into rental trucks and other large vehicles before driving away.


"This was not an organized protest," Brown said. "Rather this was an incident of pure criminality. This was an act of violence against our police officers and against our city."


The looting began shortly after midnight as people darted through broken store windows and doors along Michigan Avenue carrying shopping bags full of merchandise. Cars dropped off more people as the crowd grew.


One woman with shopping bags in her hands fell on the sidewalk as an officer was chasing her. Another woman appeared to have been pepper-sprayed. A rock was thrown at a squad car.


At least five guns were recovered, officials said.


The scene was reminiscent of the looting that occurred earlier this summer amid the response to the killing of George Floyd at the hands of Minneapolis police. Both Lightfoot and Brown implicitly criticized Cook County State's Attorney Kim Foxx, saying there weren't consequences for looters earlier this summer.


Lightfoot, who endorsed Foxx for reelection, became angry when asked follow-up questions about Foxx's handling of cases and told a reporter not to bait her.


"What we're saying is, as a result of what happened last night, there have to be consequences," Lightfoot said. "We've got teams of people that are aggressively out there identifying the people responsible, looking at the plates, and we're going to bring them to justice.


"But when we do make those arrests, our expectation is that this is going to be treated with the level of seriousness it should be. Period," she said. "Don't try to bait us, mischaracterize, pit one against the other, we're not playing that. We're in a serious situation here and we need a serious response. That's what we're saying."


Foxx's office did not immediately respond to requests for comment.


The looting seemed to be centered in Streeterville and North Michigan Avenue, but some looting was reported on State Street in the Loop and on the Near North Side. By 4 a.m. police appeared to be getting things under control.


But some vandalism continued into the daylight hours, and the CTA suspended train and bus service into downtown during the morning rush, while the Illinois state police blocked off ramps from expressways. Bridges across the Chicago River were raised, except for the one on LaSalle Street for emergency vehicles.


People were seen running out of a PNC Bank, its windows smashed, at Huron and State streets. Down the block, other stores, including a Sally Beauty Supply, had been cleaned out by vandals. Other parts of downtown, including around Grand and Wabash avenues, were littered with trash.


Crowds repeatedly tried to bash in the windows of the Omega watch store at Delaware Place and Michigan Avenue.


"The watch store," one officer said. "They're gonna get it eventually."


A group of people went in and out through a broken window of the Louis Vuitton store along Walton Place across the street from the Drake Hotel. A squad car drove by and the group ran away.


But as the car rode off, at least one person tried to go into the shop. The police returned.


"Go home!" One cop shouted.


"You go home!" Someone shouted, apparently back at the officer.


Illinois House Republican Leader Jim Durkin called for the National Guard to be brought in. The Guard was used to help enforce street closures during looting earlier this summer, marking the first time in more than a half century that a Chicago mayor had asked for the Guard's help in quelling unrest.


"Once again, Illinois government has failed to protect its residents and businesses," the Western Springs legislator said in a statement. "It is time to bring in the National Guard and accept any and all federal assistance to stop the chaos that is destroying our state. No more excuses. No more failures."


The Illinois National Guard has not received any requests for support at this time.


Lightfoot, who has fought President Donald Trump's insistence that federal troops are the best way to restore order in troubled American cities, said she will not seek military assistance. She predicted her refusal would be ridiculed by the president, who has sent federal law enforcement agents to Chicago to help with its rising crime rate.


"No, we do not need federal troops in Chicago, period, full stop," Lightfoot said. "I'm sure the president will have his way with this incident but I'm calling upon him to do the things that we do need (such as gun control)."


City officials will restrict access to the downtown from 8 p.m. to 6 a.m. for the time being. The Police Department has canceled all previously scheduled days off, and Brown has assigned a special team of detectives to review video footage.


"I don't care, I do not care, whatever justification was given for this," Lightfoot said. "There is no justification for criminal behavior, ever. You have no right to take and destroy the property of others. Our residents deserve to be safe. Our businesses deserve to understand and enjoy safety and security of their property and their employees. Our police officers deserve to be able to do their job without having to worry about shots being fired, projectiles being thrown, and being Maced. This is not anywhere near acceptable."