In total, 17 people were injured when a woman seemingly randomly attacked them with a knife at Hamburg's central station.
At least four people have life-threatening injuries and another three are seriously injured, the rescue service reports according to the German news agency DPA.
The attack occurred on a platform at the train station shortly after 6 pm on Friday.
The perpetrator, a 39-year-old woman who is a German citizen, has been arrested. She acted alone and is not believed to have had any political motive.
