A video showing a Wisconsin teacher being brutally punched in the head by a 16-year-old student reportedly led to the teen’s arrest.

The incident at South Division High School in Milwaukee began as a verbal confrontation, but the unidentified student then shoved the teacher as he was approaching him, FOX6 reported Tuesday. The student could be seen pummeling the teacher’s head as the man remained on the floor.

By the time the student stopped the assault and stood up, bystanders had already pulled out their cellphones to record the incident.

The teacher, who was also not identified, suffered non-life threatening injuries. It was unclear what class the incident occurred in.

Milwaukee police arrested the student, who faces possible battery charges, according to FOX6.

The attack happened a week into the start of the school year, TMJ4reported. A student described the teacher as “kind of like [a] helper.”

“He mostly just like, if a kid has a question, he will help them out if they are struggling or something,” Gustavo Miramontes told the news station.

A Milwaukee Public School spokesman told TMJ4 the incident is being investigated and said he could not provide further comment.