PARK RIDGE, Ill. — An investigation is underway after an off-duty Chicago police sergeant was captured on video pinning a teen to the ground in Park Ridge.

The Civilian Office of Police Accountability posted on Twitter Tuesday saying they were aware of a video published on TMZ Sunday showing a man, identified as an off-duty officer, with his knee on a teen’s back as the boy is lying facedown on the sidewalk in front of a Starbucks in Park Ridge.

Nicole Nieves on Facebook shared the video of the sergeant kneeling on the back of her 14-year-old son, Josh, as the teen’s friends yelled at the officer to get off. The incident reportedly happened last Friday.

Nieves says her son was moving what appeared to be an abandoned bike out of the way. The sergeant accused Josh of trying to steal that bike which belonged to the officer’s son. Nieves said her son had his own bike with him.

Nieves, who is Puerto Rican, said the sergeant racially profiled her son because of his skin tone. She plans to file a formal complaint.

“We’ve talked to our 3 Puerto Rican boys about this moment for years—but you can’t emotionally prepare for this happening to your own child… then it does,” Nieves said in her Facebook post. “We can’t possibly put into words how we’re feeling—disgust, anger, frustration, outrage, fear, sadness.”

Park Ridge police released a statement Tuesday and said detectives are gathering information, including video from the Starbucks where the incident took place.

Any witnesses to the incident are asked to call the police department at 847-318-5256.