Anti-terror police sealed off the German city's main train station when the attack happened at around 9pm local time (8pm United Kingdom time).
Police spokesman Rainer Kerstiens told The Associated Press that more suspected attackers are believed to be on the run.
Police were still looking for other possible suspects, a spokesman for the German federal police said.
China to boost defence spending by 7 percent
And this year's gathering is looking particularly underwhelming, summed up as it is by that least buzzy of buzzwords: stability. In this year's report, "moderate" gave way to "moderately neutral", indicating a turn toward a tighter monetary policy.
Twitter user Bruno Macedo tweeted: "Man with axe chased by police in Dusseldorf". The rail station remained shut down, he added.
Terrified passengers have taken to social media to say the situation inside the station "looks bad".
Trains also stopped running to the central station as armed cops flooded the area.
Police confirmed there was an "extensive" operation at the station following reports of "injuries".