In yet another incident of apparent anti-Semitism, a window of a synagogue in Basel, Switzerland, was smashed with a hammer on Saturday morning while congregants were inside.

The damage was discovered that morning as worshippers gathered for Shabbat services at the Chabad-Lubavitch synagogue.

There are still no suspects, according to local authorities.

“I’ve been living in Basel for 16 years. It’s the first time that I have been worried about myself and my family,” Rabbi Zalmen Wishedski, director of Chabad of Basel told a local media outlet.

Nevertheless, Wishedski said Chabad would not cancel its public Hanukkah menorah-lighting ceremony scheduled for Tuesday in the market square.

“The attackers want to intimidate us, but they will not succeed,” he said.

The incident comes after a kosher butcher shop in Basel was vandalized four times in October, in what local Jews have called an anti-Semitic campaign of intimidation.

Yaakov Haguel, acting director of the World Zionist Organization, condemned the “severe act perpetrated by criminal anti-Semites” and called on the Swiss government to take action to “eliminate anti-Semitism” in the country.

Last week, a poll by CNN found alarming anti-Semitic sentiments across Europe—namely, that one in 20 Europeans polled (5 percent) said they had never heard of the Holocaust.

In Austria, the birthplace of Nazi dictator Adolf Hitler, 40 percent of adult respondents said they knew “just a little” about the Holocaust.