People forget European soccer fans--especially the Ultras--make even the worst sports fans in the USA look civilized in comparison. Violent acts against opposing teams--especially in soccer--is sadly the norm, and after what happened at Heysel Stadium in 1985 when 39 fans were killed, English soccer teams were banned from UEFA European competition until the fall of 1991.
It’s really bad in the Slavic countries. Legia Warsaw had to play some of their Europa League games in empty stadiums because of the behavior of their fans.
Sorry, but I think you may be barking up the wrong tree for this one.
First I’m pretty sure this game was IN Dortmund, second, this just doesn’t fit the “soccer hooligan/ultra template”, especially for either team’s supporters.
That stuff is mostly ancient history.