At least two of the attackers have been caught, with fears two other suspects are on the run.
Police and emergency workers stand outside the main railway station following what police described as an axe attack on March 9 in Dusseldorf, Germany.
In July, a 17-year-old Afghan refugee wounded five people in an axe rampage on a train before police shot him dead.
One photo from the scene shows paramedics treating someone lying on the ground, taped off by a cordon.
Hype For Brock Lesnar vs. Goldberg At WWE WrestleMania 33
The pay-per-view will cost £14.95 for viewers in the United Kingdom and €21.95 for customers in the Republic of Ireland. And with Sasha Banks winning to Nia Jax, this sets up the return of Banks to becoming a heel and turn on Bailey.
"People travelling were injured by the assailants' axes", the police said, adding that it was unclear exactly how many attackers were involved.
The man arrested was also injured, spokeswoman for Dusseldorf police Anja Kynast said. The train station remains closed and trains have been diverted.
Terrified passengers have taken to social media to say the situation inside the station "looks bad".
Trains are reportedly not stopping at the station.