(JTA) — London police are investigating a series of anti-Semitic tweets posted following a Football Association Cup game between rival soccer teams Arsenal and Tottenham Hotspur.

The tweets, posted on Twitter by Arsenal supporters, mostly referred to the Holocaust. “Every Tottenham fan can be put back in the gas chambers and gassed to death,” read one tweet.

Police opened the investigation on Tuesday, following the game on Jan. 4.

Tottenham Hotspurs is known as the “Jewish” team of London because of their large Jewish following and its fans are often referred to as the “Yids.

In September, the English Football Association announced that the use of the term “yid” at games is inappropriate and that fans could face criminal charges for using it. Fans call the term a compliment.