The incident took place at about 1800 hrs (GMT). According to earlier reports, the suspected attacker sustained wounds and was detained.
According to the Bild newspaper, there are four victims of the attack, with at least one of them being in a life-threatening condition.
A police spokesperson told the DPA news agency, that there is no evidence that the assault had a terrorist motive. The exact reason remains unknown but it is likely to be a family dispute, the spokesperson added.