A 48-year-old man was brutally beat by some teenagers as a crowd watched the assault, filmed it with their cell phones and chanted "USA! USA!"
The brutal assault happened in Hinkley Park on July 12 in Park Ridge, which is a suburb of Chicago.
A cell phone video (below) posted by the Park Ridge Herald-Advocate shows the victim in a yellow shirt being knocked to the ground and beat by three unidentified males as the crowd cheers.
When the man tries to walk away, he is pushed down again by an attacker before an unidentified teen bravely places himself between the victim and the suspect.
The victim, who reportedly suffered a concussion, was at the park looking for his son during a fireworks show.
Apparently, someone threw a lit firework near the victim, but when he asked who did it, a crowd of 200 young people surrounded him and the beating soon began.
According to Park Ridge Police Officer John Dorner, this cell phone video is much like other videos that police have viewed of the incident.
CBS Chicago reports that Park Ridge police have charged three teens in connection with the attack: Jordan Gonzalez, 18, Mac Piazza, 18, and a 16-year-old boy whose name was not released because of his age.
Gonzalez and Piazza were held in the Cook County Jail as of Thursday afternoon. If they post bail, both teens will have to wear an electronic monitoring device, according to Park Ridge police.
Police are still investigating the incident, but no more arrests are expected.
Authorities want to locate the brave teen who stopped the beating, and thank him.