(JTA) — German police officers wrestled to the ground and arrested a middle-aged Israeli academic wearing a kippah after he was assaulted in a park allegedly by a 20-year-old man with Palestinian roots.

The incident, which is believed to be an anti-Semitic assault, happened in Bonn on Wednesday, according to the DPA news agency. Police apologized for what they said was a mix up. The alleged assailant was taken to psychiatric institution for observation and released shortly after the incident, pending criminal charges, RP Online reported.

The complainant was an Israel-born 50-year-old professor of philosophy from the University of Baltimore, who was visiting Bonn to deliver a lecture, the report said. He was wearing a kippah at the time of the incident.

The incident happened at around noon at a local park where the professor and a friend were strolling in a local park. The suspect then shouted at him anti-Semitic insults in English and German, including: “No Jew in Germany!” and knocked the kippah from the professor’s head, according to the report. The alleged assailant then shoved the professor and hit him on the shoulder. The professor defended himself as his friend fetched police – who wrestled to the ground the professor but not the alleged assailant.

The professor’s name was not published in German media.

“Media reports on how the incident was handled are deeply disturbing,” said Rabbi Abraham Cooper, associate dean of the Simon Wiesenthal Center. He added: “It is difficult to fathom how a middle-aged professor wearing a kippah would be identified as the perpetrator.”

The incident follows a spate of anti-Semitic assaults in Germany, including of an Israeli Arab who wore a kippah in Berlin in April to prove to a friend that doing so was safe. An assailant shouted “Jew” at him in Arabic while whipping him with a belt.

A Berlin-based center on anti-Semitism in April said that a 60 percent increase in anti-Semitic incidents occurred in 2017 over the previous year. According to the Research and Information Center on Antisemitism, or RIAS, 947 incidents were reported last year, compared to 590 incidents in 2016.