I Don't Get Sports Fans

Bomb scare? Hostage taking?

There were four police vans at the Hauptbahnhof (train station) in Dortmund when we were ready for the return trip to Witten. Two came and left while we were waiting. Each van carried at least five police officers, some of them in riot gear.
When I asked what was happening, I was told there was a soccer game that afternoon and fans from Bremen were coming to watch. Fans congregate at the train station and start to drink and celebrate before they make the trek to the soccer stadium. They bring their beer and food and generally plan to make a day of it.
There is no law here against drinking in public; the police only intervene if things start to get out of hand. However, judging by the police presence, I would say that in the past that is exactly what happened.