Chicago Police Superintendent David Brown said two groups of people were fighting in the 800-block of North State Street at about 10:41 p.m. when someone in the crowd began firing shots.
WATCH: Man wounded in Near North Side mass shooting recounts chaos
The shots were fired just as police arrived to break up a fight between two large groups.
"All of a sudden who bunch of gunfire went off, man. Whole bunch of gunfire went off," said a witness who asked to be identified only as Mark.
The shooter then fled down to the CTA subway platform and members of the shooter's group fled with him, police said.
Police chased the suspect and arrested him in the subway station and a gun was recovered. Brown said they are working with the Cook County State's Attorney's Office on charges.
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Brown said a pod camera in the area captured the shooting and one person was arrested for obstructing officers on the CTA platform.
Officials said a woman fell against the third rail in the midst of the chaos. She was transported to the hospital with burn wounds, but her condition was stabilized, police said.
The Chicago Fire Department said one man was taken to Northwestern Memorial Hospital and another to Stroger Hospital. Both were pronounced dead at the hospital. Authorities have not released information on their identities.
Two other adult men were transported to Northwestern Memorial Hospital and Stroger Hospital in serious condition, CFD said. A 43-year-old woman was transported to Illinois Masonic Medical Center in stable condition.
Mass shooting on Near North Side captured on pod camera, Supt. Brown says
Brown said a person was seen on video handing the shooter a gun and they are working to identify that person.
Police said nine people were taken to hospitals or walked in themselves:
-A 31-year-old man was shot in the back and pronounced dead at Stroger Hospital
- A man was shot in the chest and pronounced dead at Northwestern Memorial Hospital
-A 19-year-old man was shot in the chest and transported to Northwestern Memorial Hospital in critical condition
- A 17-year-old boy was shot multiple times and transported to Stroger Hospital in stable condition
- A 36-year-old woman was shot in the leg and transported to Illinois Masonic Medical Center in stable condition
-A 31-year-old man walked into Northwestern Memorial Hospital in good condition with a wound to the hand
-A 21-year-old man was shot in the lower leg and walked into Northwestern Memorial Hospital in good condition
-A 30-year-old man suffered graze wounds to the shoulder and stomach and walked into Northwestern Memorial Hospital in good condition
-A 29-year-old man suffered a graze wound and walked into Northwestern Memorial Hospital in good condition
The McDonald's at the corner of State and Chicago is now closed until further notice. According to a sign on the door, the location has been deemed "dangerous and hazardous." Mayor Lightfoot said in her afternoon news conference it will not be allowed to reopen until it is brought back into compliance on building issues.
'It escalated quickly,' shooting victim says
Shaun Davis, 29, said he was inside the McDonald's when people started fighting outside.
"It escalated quickly to where some guy popped out with a gun," Davis said. "My guys tried to grab the gun, but in the midst of them grabbing the gun, it slipped my way and a shot popped out."
Davis said he was shot twice. Once on his side and once in the leg. He was taken in an ambulance to Northwestern Memorial Hospital.
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Paramedics rushed in to help and treated people right on the street. Many fights were breaking out at the time, with officers trying to break them up.
"We walked across the street to the store and next thing we know, people started shooting and everybody just got hit," Deonna Jackson, witness said. "My first instinct was just run because I have been hit before."
A man described two girls who came crawling into his nearby apartment lobby on the floor - in terror.
"They looked absolutely terrified," Micah, who lives nearby, said. "They looked like, just traumatized honestly and I didn't fully know what happened until I came out here."
The shooting impacted service on the CTA Red Line overnight, with normal service resuming early Friday morning.
Mass shooting 'outrageous' act of violence, Lightfoot says
Mayor Lori Lightfoot spoke out about the shooting Friday morning, calling it "outrageous and also saying it is like "déj vu."
"It's hard to stand here day after day and see this happening in our city," Mayor Lightfoot said. "Because it is a tragedy. I didn't use the word 'senseless violence' because there is no violence modifier. Violence is wrong. Violence tears apart our families and the fabric of our city. It's with a very heavy heart that I stand here before you today."
In the wake of the shooting, the mayor asked Supt. Brown to install a fixed post of uniformed officers at the intersection of State and Chicago and a separate fixed post in the Chicago Red Line station. Brown said that will be in effect immediately.
Lightfoot has also engaged the Department of Business Affairs and Consumer Protection to determine what if any additional measures need to be taken to address the long-standing concerns along that block.
Brown said it is a gun crime crisis.
"We are awash in guns and I would continue to beat the drum of consequences in the courts for people who have violent crime histories who are then arrested for possessing a gun illegally," Brown said. "They should not be released."
Second Ward Alderman Brian Hopkins says it's going to take detectives hours, if not days, to comb through all of this video footage.
"I'm hearing from people who have lived in the city their whole life and they tell me the same thing: They've never been as frightened as they are right now," Alderman Hopkins said. "When things like this happen, it just hurts your heart as a Chicagoan who loves the city. We simply can't live like this and our city can't survive unless we find a way to stop this."
Mayor Lightfoot released a statement on the shooting, saying, "An outrageous act of violence was committed last night in the area of Chicago and State. I have been in frequent contact throughout the early morning hours with Superintendent Brown and his team, as well as President Carter of the Chicago Transit Authority (CTA), and I will continue to monitor developments throughout the day.
"Area residents, commuters, and others simply must have the peace of mind that this highly trafficked area is safe, and it is time for more specific, concrete steps to be taken to address this area once and for all.
"First, I have asked Superintendent Brown to install a fixed post of uniformed officers at the intersection of State and Chicago and a separate fixed post in the Red Line station in the same area.
"Second, I have also engaged the Department of Business Affairs and Consumer Protection to determine what if any additional measures need to be taken to address long-standing concerns along that block. That work has already begun.
"Lastly, I have asked the Chicago Police Department (CPD) and CTA to continue to work together to have our CPD Public Transportation Section with visible patrols of stations, platforms, and trains 24 hours a day, seven days a week.
"Most importantly, it is simply awful, and unacceptable that once again, another tragedy occurs because firearms are in the hands of people who simply do not care about themselves or the value of another's life. Our police department is hard at work to make sure those responsible for last night's incident are held accountable, for the safety and well-being of us all."
Further information on the circumstances of the shooting were not immediately available.