(JTA) — Teenage hecklers interrupted a South African Jewish school’s performance of a play about the Holocaust with chants of “Heil Hitler!” and other anti-Semitic taunts.

Middle-school children from the King David Victory Park School were performing “The Boy in the Striped Pajamas” on May 18 as part of a one-act play festival at Waterstone College, a private K-12 school in Johannesburg. While they were performing the story of a Jewish boy who perished in a concentration camp, teenagers in the audience from another high school began to taunt them.

“They were chanting ‘Heil Hitler, Heil Hitler.’ I was shocked and disgusted. I couldn’t believe what I was hearing, “Alic Gluch, a 14-year-old King David student, told the South African Jewish Report.

The teenagers continued to taunt the Jewish students, their teachers and parents as they retreated to the dressing rooms and packed up early to leave.

Witnesses said the ringleaders were students from Edenvale High School, which was also participating in the festival.

Renos Spanoudes, who heads the drama department and arts and culture at King David, said in a WhatsApp message that an Edenvale High teacher downplayed the seriousness of the incident, while some of the Edenvale students said they were ” very, very sorry.”

Wendy Kahn, national director of the South African Jewish Board of Deputies, said her group was seeking a meeting with the the principal of Edenvale High “to address this issue and determine a constructive way forward.”

“From time to time anti-Semitic incidents of this nature occur during interschool events, both in the cultural and sporting arenas,” she told the Jewish Report. “We have in the past been involved in addressing these incidents. We do not believe that this is an indication of an upsurge in anti-Semitism. ”

The headmaster of Edenvale High did not respond to the Jewish Report’s requests for comment.