Joshua Beal was killed Saturday afternoon in the city's Mount Greenwood neighborhood after a traffic dispute.
On Monday, Chicago police said the cellphone video is authentic and not altered. The video shows a chaotic scene of shouting and shoving mostly white men on the left side of the screen and African American women on the right.
CPD detectives have authenticated the private cell phone video and photographs from yesterday's. incident in 22nd District.— Anthony Guglielmi (@AJGuglielmi) November 7, 2016
Detectives are thankful for all the information coming in from the community and citizens in the area.— Anthony Guglielmi (@AJGuglielmi) November 7, 2016
A man in red, identified as an off-duty officer by sources, is seen pointing a weapon at the group of women. He then puts the weapon into his waistband.
As the camera swings right, it shows a man a car length away from the argument raising his hand for two seconds with what looks like a weapon. The man was Beal, Chicago police said.
The fatal shooting of Beal occurs after the video ends and after other officers arrived on the scene.
The Independent Police Review Authority (IPRA) is investigating.
"IPRA investigators are in talks with several eye witnesses and are taking steps to authenticate the videos and images that have been widely circulated. While it is still very early in the investigation we can confirm that early ballistic evidence suggests multiple firearms were discharged. It is our hope that people will wait until all evidence is brought to light before making any conclusions about what happened yesterday evening," said IPRA spokesperson Mia Sissac.
An off-duty firefighter was in a separate altercation nearby when the shots were fired, sources said.
A photo captured the firefighter, who ran toward the scene, trying to save Beal after the shooting.
Beal's brother, Michael Beal, was arrested Saturday in connection with the incident.
He was charged with aggravated battery to a police officer, resisting arrest and attempting to disarm a police officer. He is due in court on Tuesday.
The two Chicago officers involved in the incident are on administrative leave.
The incident sparked clashes between two groups near the site of the shooting.
On Sunday, Mount Greenwood residents squared off against activists demonstrating against the shooting. The clash between Black Lives Matters and Blue Lives Matters groups became tense at times as they exchanged chants such as "KKK" on one side and "CPD" on the other side.
On Monday, Marist High School said it is taking action after a student's racially charged post on social media reacting to the shooting.
This statement was posted on the school's website: "This evening Marist High School was made aware of a racially charged post on social media involving Marist students. We are devastated by this situation. Disciplinary action is being taken. Marist is a diverse community, made better and stronger by that diversity. As a school community, we continually work so that each student feels welcome, valued, and safe. We have been and will continue to engage with diverse student leaders to give a voice to all students and to focus on shared values. Given the tenuous times we all are living in, and recent events nearby Marist High School, our mission to make Jesus known and loved is more pertinent than ever. As always, the safety of our students is of utmost importance."
WATCH: MARIST STUDENTS DISCIPLINED AFTER RACIAL SLURS
Five students were involved, Marist administrators said. They hope to use the incident as a teachable moment.
Marist principal Larry Tucker said he was devastated by the messages.
"It's an excellent opportunity for us as a Catholic school to approach this not just as a social issue, but as a moral issue," said Hank Hammer, Marist president.