The police officers are currently in Kaiserstrasse while they assess the situation. Cordons have been set up to protect the public, with members of the raid squad armed with heavy weapons. It is not yet known if anyone has been injured.
A police spokesman said the operation has been in place since 1pm local time.
The spokesman also confirmed that “shots were allegedly heard” by onlookers.
According to social media reports, the incident took place near the station distract.
One person wrote: “Avoid the station district in #Frankfurt! She @FRlokal reports gunshots there in the city center.”
Shortly before 3pm local time, police said they had called a halt to the operation.
They said the alleged gunshot noises were actually stones that a stranger had thrown at the windows.
The person was provisionally arrested.
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Additional reporting by Monika Pallenberg