Widespread looting took place in Chicago overnight, with Apple, Old Navy, and Tesla stores among those hit during the riots.
The mayhem caused the city to raise bridges to cut off access to downtown, according to photographs and video footage.
"This was an assault on our city. It undermines public safety and breeds a sense of insecurity among our residents," Mayor Lori Lightfoot, a Democrat, told reporters in a press conference on Monday morning.
"What occurred in our downtown and surrounding communities was abject criminal behavior, pure and simple, and there cannot be any excuse for it, period."
The rioting started late Sunday, Chicago Police Superintendent David Brown said.
The mayhem appeared to stem from outrage over a police shooting earlier in the day.
Officers responded to a call in the Englewood neighborhood about a man with a gun and tried to interview him but he fled. As he was moving away, he pulled out a firearm and fired shots at the officers, who returned fire.
The 20-year-old man was rushed to the hospital.
A crowd gathered in the area and began shouting at the police.
"Tempers flared, fueled by misinformation as the afternoon turned into evening. CPD became aware of several social media posts encouraging looting downtown," Brown said.
Four hundred officers were dispatched to try to stop the looting but dealt with so-called car caravans streaming into the heart of the city, targeting dozens of stores, including a Best Buy, an Apple store, and clothing businesses.
Over 100 people were arrested on charges including burglary and disorderly conduct.
Some looters resisted arrest. Thirteen officers were injured, including one who had his nose broken while fighting with criminals.
While officers were arresting one looting suspect—who was walking out of a store with a cash register—a vehicle passed by them, and someone inside opened fire.
Officers returned fire.
It wasn't clear whether anyone inside the car was struck. None of the officers were hit.
Officials vowed to hold criminals responsible for the crimes and urged the public to help them identify the looters.
Harsh measures are being imposed to try to prevent another night of unrest. Access to the downtown is being restricted from 8 p.m. to 6 a.m., with an enhanced law enforcement presence staying in place until further notice.
"CPD will not stand by as our beautiful downtown becomes some place that people fear," Brown said.
The police department is creating a special team to pore over the hours of footage captured downtown.