About 1,000 police officers at Saturday's Revier derby between Borussia Dortmund and Schalke used water cannons and pepper spray to combat fans from both sides as they fought them with cobble stones, bits of restaurant furniture and most everything else they could find. The clashes began before the match, which Schalke won 2-1 to give Dortmund its first home loss in over a year, when the extra-large police contingent tried to keep the two sets of rival fans separated outside the stadium.

From ESPN:

According to local police reports, a restaurant was gutted by Dortmund followers "with furniture ripped apart and used as missiles against opposition fans and police''. One police car was damaged as mounted police, riot police and agents with dogs were brought in to keep the spectators apart. Followers of both clubs attacked police who tried to segregate them in the Westphalian city and water cannons and tear gas had to be deployed to keep them at a safe distance. Mounted police were "attacked by Dortmund hooligans with cobble stones'', according to a police report.

The trouble continued during and after the match, resulting in over 200 arrests and eight injured officers.

Here's video of the police clearing a large standoff outside the stadium...