CHICAGO — A student walkout is planned Monday afternoon at Chicago’s Jones College Prep School.

Students are angry that a classmate showed up to school on Halloween wearing a costume that appeared to be a Nazi soldier uniform. In video clips shared on Twitter, the student can be seen goose stepping across a stage as several others loudly boo him.

The high school’s principal, Joseph Powers, has been suspended as the district investigates.

Powers told students and parents that the uniform actually copied those of East German board guards in the 1980s, not Nazi solders from the 1940s.

But, Powers conceded that some students recognized it as an act of antisemitism.

In an email sent to the Jones community Thursday, Powers wrote:

“Let me say clearly and plainly that what occurred caused harm to many of our students and staff who recognized this as an act of antisemitism. Let me also say clearly and plainly that intolerance, bigotry, and bias-based behaviors have no place in our school … We want you to know that we are addressing this situation directly with the member of our school community who wore the costume in accordance with protocols for processing bias-based harm.”

The Chicago Teachers Union is call for Powers to resign.