The flag was discovered by a school alumna who posted a photo on social media.

A Frederick County, Md., high school is under investigation after alumni spotted a Nazi flag hanging inside a classroom and posted the “hateful” image that went viral on social media.

As spectators were heading into Governor Thomas Johnson High School on North Market Street to watch a boys’ basketball game on Friday night, a large Nazi flag was on display inside a window near the entrance.

Nicole Hopkins snapped a picture of the red, black and white cloth and posted it on her social media on Saturday, according to The Frederick News Post. The photograph was then shared publicly by Serenity Bush Moore, who alerted her followers to contact the Frederick County Public Schools [FCPS] administrators.

“As a graduate of FCPS, I am so regularly disappointed by their poor decisions. The idea that a school system has made a decision to exist in the destructiveness and incapacity dimensions of the cultural continuum demonstrates a total inability to protect all students,” wrote Moore. Her post has been shared almost 450 times with almost 1,000 comments.

Hours after the photograph circulated on social media, the FCPS issued a statement apologizing to the community and explaining that the flag was inside a classroom where World War II history was being taught.

“FCPS sincerely apologizes to our community for this incident as we share your feelings regarding the hatred and intolerance message this flag represents,” read a statement posted on FCPS’ Facebook page.

The flag was taken down and “due diligence” from the staff was promised on Monday “to identify the events leading to this unfortunate incident. We will take the appropriate steps to ensure an incident such as this is not repeated. The values of FCPS are in direct contrast to the message represented by that flag, and we apologize that the display of this flag caused hurt in our community.”

Moore wasn’t buying it.

“Please miss me with it’s a social studies class. What culturally proficient educator has a ‘life’ size Nazi flag in their tool kit and then has the audacity to hang it OVER THEIR CLASSROOM WINDOW IN THE FRONT OF THE SCHOOL BUILDING BY THE MAIN ENTRANCE,” Moore wrote. “Staff and administrative parking is directly in front of this window, so this was seen by a school leader. Irresponsibility and privilege at its highest levels.”

Request for comment from the county’s superintendent, Dr. Theresa Alban, on Monday’s investigation was not immediately returned.