The man who recorded the video, Emmitt Reynolds, showed up for his overnight shift at a downtown office building not expecting anything out of the ordinary.
But he certainly was a perfect witness when a motorist emerged with a knife after an early morning car crash.
In daylight, it looked like any scene out of a blockbuster Hollywood action movie.
"I was a little nervous, but I pulled out my camcorder and started recording," said Reynolds.
But Reynolds says it was anything but that as he and a dozen others witnessed the shooting of the knife-wielding motorist by a Chicago Police sergeant,
The Chicago-area resident was at his downtown Loop job when he heard a collision that witnesses say began when the driver of a black Nissan Maxima rear-ended a silver Chevy Malibu causing it to spin out and the Maxima to hit a light pole.
"I came outside and saw a lot of commotion," Reynolds said. "I came down the street and what I saw was two construction workers tussling with a guy."
At that point, Reynolds had no idea what he was about to capture on his cell phone.
It was just before 2 a.m. Saturday morning when the crash happened near LaSalle and Monroe.
"When he got out of the car, the lady got out of her car, and he had a knife in his hand," witness Ernest Hoddes said.
That's when the driver of the Maxima allegedly tried to attack the female driver involved in the accident he apparently caused.
Police say the man even stabbed a private security guard as she tried to intervene.
That is when an on-duty Chicago Police sergeant arrived and told the driver to drop the weapon.
"He was swinging the knife, and the officer kept telling him put it down, put it down," witness Stanford Kimbrough said.
But when the driver refused and came towards the sergeant, she fired, striking the man in the lower leg.
"She told him to put the knife down," Hoddes said. "He tried to reach for her gun, and she shot him."
The man was then subdued.
The suspect, the wounded security guard, and the two women injured in the crash were all taken to area hospitals.
Saturday afternoon, Reynolds was still amazed by the moments he captured while praising the sergeant for her selfless actions.
"I definitely think the shooting was justified," he said. "I don't think it was wrong or nothing."
It is still unclear which two people were taken to Northwestern Memorial Hospital in critical condition.
Two others were taken to Stroger Hospital.
Police have still not said what charges the knife-wielding motorist will face.