Video of a Baltimore school officer slapping and kicking a teenager -- while another officer watched -- led city law enforcement to open a criminal investigation on Wednesday.
The incident happened on Tuesday after two officers were called to investigate two supposed intruders at REACH Partnership School.
Officials at the school said they weren't able to identify the two people as students.
The lawyer for the unidentified 16-year-old in the video said the teen is listed as a student at the school, though he does not go to class, according to The Baltimore Sun.
The 16-year-old suffered injuries to his face and ribs and was treated at a hospital.
"I am completely appalled and disappointed by what is depicted in the video," Baltimore Schools CEO Gregory Thornton said in a statement.
Baltimore residents have long called for reforms amid police in the school system.
At the start of last year, video surfaced of a 2014 incident in which an officer assaulted middle school students.
The female officer got into an altercation with three female students and hit one several times with a baton. One student wound up bleeding from the head.
The officers involved in this latest incident are now on administrative leave, as is School Police Chief Marshall Goodwin. The police department's Special Investigation Response Team will handle the investigation.