A Brinks truck appeared to be the center of the investigation as police said a man tried robbing the security guard and was eventually shot.
Police said a security guard was leaving a business near Madison and State Street at about 11:19 a.m.
A suspect approached him and tried to rob him, officials said.
Police said there was a struggle between the suspect and the security guard, when the security guard pulled out a weapon and fired shots.
The suspect ran off with the stolen items, however, police said he was placed into custody shortly after.
Chicago police said the suspect was shot multiple times. He was taken to Northwestern Hospital, where his condition was stabilized.
Blue Line trains were bypassing the nearby Washington station due to the police activity, CTA officials said. Normal service has since resumed.
Chicago Public Schools issued a statement, saying "The CPS entrances at 42 W. Madison St. and 1 N. Dearborn were closed due to an active crime scene in the area. CPS staff was permitted to exit a dock entrance/exit the entire time. The doors at Madison and at Dearborn were later re-opened. We informed our central office staff of the limited entrance and exits via email and our internal Public Address system."
A Brink's armored truck was seen at the scene. A Brink's spokesperson told ABC7 they do not comment on open law enforcement investigations.
"Your nerves go a little bit crazy," witness Theresa Bowick said. "I'm a nurse so I'm used to blood, but I got myself settled. I'm worried for Chicago."
One man named Kodi witnessed the shootout and said he saw two other men involved in the attempted robbery.
"Security guard ended up shooting one of the dudes," Kodi said. "Two of them ran off kind of splitting ways and the other one just dipped out to the street and tried getting to the subway. There was just blood everywhere and I guess he ended up collapsing near the subway."
Police say no one else was hurt, but it was a startling scene for many people working in the Loop.
"I'm not really used to this level of crime but it's a beautiful city and I just hope for change and hope for improvement," said a man named Kevin who works nearby the crime scene.
No other injuries were reported. CPD said charges are pending.
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