German authorities are investigating after up to 200 men attacked police at Cologne's main train station in what authorities called a "massive riot".
A spokesman for the federal police said fans of Bundesliga 2 club FC Kaiserslautern threw fire extinguishers and metal bars at officers on Saturday, injuring two of them.
Rail traffic was halted during the attack.
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Police spokesman Jens Floren said the attackers were traveling home from Dusseldorf following Kaiserslautern's 4-3 defeat to Fortuna Dusseldorf.
Floren said alcohol may have played a role but "one can assume that a large share of them were proper hooligans".
Police are examining the video footage before pressing charges.
Violence in Cologne on New Year's Eve, blamed on foreigners, sparked outrage and a national debate about integration.