A shopping mall in the center of the western German city of Essen was ordered by police to remain closed on March 11 due to "concrete indications about a possible attack."
"The current state of our investigations points to the threat being exclusively at the shopping center," police said in a statement, without giving further details.
Police told the German news agency dpa that there were indications that the center was about to be targeted by terrorists, therefore the decision was made to close the facility for the day.
Germany is on high alert following major radical Islamist attacks in France and Belgium, and after a failed asylum seeker from Tunisia drove a truck into a Christmas market in Berlin in December, killing 12 people.