In Hagen in North Rhine-Westphalia, the police are investigating evidence of a possible risk situation at a Jewish facility.
The Dortmund police announced this on Wednesday evening.
"Police protective measures have been adapted accordingly.
We are in close contact with the Jewish community. "
A police spokesman said on request that there were emergency services on site.
For tactical reasons, however, further details should not be given.
According to several media reports, the police are on site with a large number.
Wednesday and Thursday is Yom Kippur, the highest Jewish holiday.