CHICAGO — Hundreds of young people looted stores, broke into indoor shopping malls and battled with police overnight Sunday into Monday in the city’s central downtown business district.

The reason for the unrest, according to several looters who spoke to The Washington Post on Monday, were reports alleging a police-involved killing of a Black man on the city’s South Side late Sunday afternoon. But police said those accounts were misinformation spread across social media that appeared to encourage people to head downtown to create violence.

Chicago Police Superintendent David Brown said Monday that officers responded to a call about a man with a gun in the Englewood area; once spotting the man, they pursued him on foot. After the man shot at them, police said, the officers returned fire. The man, 20, is now recovering at the University of Chicago Hospital and is expected to survive, police said.

“This was not an organized protest. This was an act of pure criminality,” Brown said.

Chicago Mayor Lori Lightfoot (D) added: “This was brazen and criminal looting and destruction. … This is not anywhere near acceptable.”

During the unrest, officers shot at least one person and chased suspects toting bags full of goods, tackling some to the ground and blocking off streets as they sought to restore order to the area. The looting came after a tense day between police and Black residents after the exchange of gunfire in the city’s South Side, sparking a violent standoff between dozens of officers and angry neighbors.

A crowd quickly gathered nearby, and tempers flared after police allegedly took a cellphone away from someone who had recorded the shooting. Soon, rows of police faced off with a rapidly growing group.

In the looting that followed later downtown, videos show people roaming up and down the streets, bashing their way into stores including Neiman Marcus, Nordstrom Rack and a Tesla dealership. As police closed off highway ramps, bus and train service was halted downtown at the “request of public safety officials,” the city’s transit agency tweeted.

Thirteen of the 400 Chicago police officers dispatched downtown were injured during the night by bottles and physical attacks. Many were shot at, Brown said, and a security guard and a bystander were injured and are in critical condition. Police recovered five guns.

The looting, which spread south into the Loop and also into the North Side’s Old Town neighborhood, was a reminder of the chaos that followed the killing of George Floyd, an unarmed Black man, in the custody of Minneapolis police less than three months ago. At the time, Illinois Gov. J.B. Pritzker (D) sent 375 National Guardsmen to protect the downtown area, freeing up Chicago police to handle the looting that had spread throughout the city and surrounding suburbs. The unrest lasted for about a week after Memorial Day.

Lightfoot told reporters at a second news conference Monday morning that she has not asked Pritzker for National Guard help, despite calls from Republican state lawmakers for state and federal troops to be sent in.

“No, we do not need federal troops in Chicago — period, full stop,” Lightfoot said.

Pritzker told reporters that the state police were dispatched last night. “Anything and everything we are asked to do, we will be helpful,” he said.

Chicago’s downtown is now closed indefinitely between 8 p.m. and 6 a.m. Police will be dispatched to outlying neighborhoods to prevent continued looting this week, Brown said. Cook County Circuit Court Chief Judge Timothy Evans ordered the closing of all courts, with the exception of bond courts. A ribbon-cutting ceremony in Englewood for a new restorative justice court also was canceled.

The looters arrived downtown in cars about 1 a.m. Police had major intersections blocked off, but that did not stop groups of mostly young people roving through the district of high-end retail stores, smashing windows and stealing goods. Clothes hangers and smashed glass covered sidewalks along North Michigan Avenue. Water Tower Place, the district’s premier indoor shopping mall, was broken into on both its west and east sides. Looters shattered windows of convenience stores and retailers including Macy’s, Ralph Lauren and Express.

Two boys, ages 14 and 15, said they were downtown because “of the same situation as before — killing an innocent Black person.” A woman who was quickly walking while carrying a Target basket filled with goods said she and her friends went downtown because they “felt like starting a riot.”

The violence terrified people staying downtown. One couple that headed to a Walgreens for cold medicine ran into the looters along the way. They said it appeared as if the violence had been planned.

“They were all getting out of cars and heading straight to the businesses,” said a 33-year-old restaurant manager who spoke on the condition of anonymity because he feared reprisals. He said he was part of a crew that helped other restaurants clean up during the first round of looting in early June. “This is the new normal. At this point you become desensitized to it.”

Brown suggested that looters are newly emboldened by the reform efforts that Cook County State’s Attorney Kim Foxx (D) and her office have implemented and that he views as being lenient in charging felony offenses.

“Criminals took to the streets with the confidence there is no consequence for their actions,” Brown said.

A Chicago Tribune investigation found that during Foxx’s first three years, her office dropped all charges against nearly 30 percent of felony defendants; during the same time period of her predecessor, the rate was 19 percent.

Lightfoot was more direct about the need for the state’s attorney’s office and the courts to “step up.”

“Put your best people on this,” Lightfoot said. “We have made the case — we have the video, we have the officer testimony — that these people need to be held accountable and not cycled through the system. And judges that are holding these cases — you need to step up and be responsible. We can’t continue to allow this to happen, for people to believe there is no accountability through our criminal justice system. No one wants to hold people in jail because they are poor. But people who are engaged in this kind of criminal activity, they need to be held accountable. And we cannot do it alone.”

Speaking with reporters Monday, Foxx suggested that the police department has not brought her office enough cases that warrant felony charges.

“Our office is not in the arresting business,” she said. “We get cases when they are brought to us.”

Of the 5,000 arrests made following Floyd’s killing through late June, just 29 percent were felony cases, she said. Court dates for those arrests start this month. About 1,000 were misdemeanors and another 1,000 were for violating city ordinances, she said. About 500 involved people who were taking part in peaceful protests and they face charges such as breaking curfew.

“I understand the superintendent and mayor’s frustration,” Foxx said, noting that her office has been diligent in pursuing felony cases. “I share their frustration.”

She also noted how 2020 “is unlike any year we have seen.”

“We’ve seen a global pandemic coupled with civil unrest coupled with economic depression, and we see the violence we see now,” she said. “We need to talk about reflection beyond a sound bite and a finger point.”

Elfrink and Armus reported from Washington.