Two suspects were arrested by German anti-terror police, according to the reports.
As many as five people are reported to have been hurt, although the extent of their injuries is not yet known.
Two suspects are believed to have been detained by police but the motive for the attack is now unknown.More news: Andrew Bogut injured early in Cleveland Cavaliers NBA debut against Miami Heat
Shocking images show injured passengers lying on the floor in the station, surrounded by paramedics. "Station closed. I am in the train things look bad #police #terror".
The man arrested was also injured, spokeswoman for Dusseldorf police Anja Kynast said.
"We were standing on the track, waiting for the train", a station attendant told the German newspaper Bild.
Trains are reportedly not stopping at the station.