The Australian police have reportedly launched an investigation after a large group of anti-Israel protesters stood on the steps of the Sydney Opera House and chanted, “Gas the Jews.” The phrase is in reference to Jewish people being forced into gas chambers under Hitler’s rule during WWII.

The protest included about 1,000 participants who gathered outside the Sydney Opera House Monday night, where many were apparently carrying Palestinian flags and setting off flares. The footage was shared by the Australian Jewish Association and featured individuals chanting, “Gas the Jews,” “F**k the Jews,” and “Allahu Akbar.”