Trouble started with some 1,000 Schalke fans arriving in Dortmund, lighting flares on their way to the stadium and fighting with rival fans and both attacking police who tried to separate them.
Police used a water cannon to stop Schalke fans trying to destroy a fence while mounted police were also attacked with stones.
Police said fans had also destroyed a snack bar near the stadium, breaking it up and using parts of it as missiles.
The two teams are among the most fervently supported in Germany and despite have one of the biggest and longest-running Bundesliga rivalries being only a few kilometres apart.
"Dortmund and Schalke's violent criminals consciously undermined our security concept and arrived ready to conspire," said Dortmund police director Dieter Keil. "Their aim was to fight their rivals and innocent people."
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