A white teacher in Chicago has been suspended from teaching after he hung a Black doll from a cord at the front of his classroom. As the Chicago Sun-Times reported, the teacher, who teaches history at the Whitney Young Magnet High School, has been pulled from his classes as the investigation into the incident continues.

“[The school] has a responsibility to provide a safe space for every member of our school communities, which is especially important in a district that serves a student population that is 90% Black and Brown children,” the Chicago Teachers Union said in a statement. “We understand the investigation at Whitney Young is ongoing, but practices that mitigate the harm of racial biases must also be ongoing and consistent in our schools. And any definition of ‘safety’ must include creating and reinforcing an environment of equity and inclusion for all students, staff and faculty of color.”

Per the Sun-Times, the union was not the only one to take issue with the acts of the white teacher. After seeing the doll —a football player in a blue uniform— hanging by a cord at the front of the classroom, a Black teacher grew offended, and the two eventually got into a heated argument. Clips from the exchange were taken by students and spread throughout the internet, getting the attention of the school’s leadership. Now, Principal Joyce Kenner and administrators from the high school are teaming up with Chicago Public Schools’ Title IX office “to not only investigate and respond but to elevate student voice in the process.” They’ve already begun to conduct listening sessions for the kids to ask questions and express their concerns.

Also upset with the white teacher are hundreds of individuals who signed a petition calling for his termination. Per the Sun-Times, more than 400 signatures were collected.