Just to clear things up: http://www.nu.nl/binnenland/4102401/aanhangers-vitesse-nog-vast-rellen-in-arnhem.html
It says supporters Vitesse are still being held by police for the fights from yesterday. Mentioning no Feyenoord-fans were involved and apparantly it was just a rumor spread by some locals and a local paper. Feyenoord is like the black sheep amongst Dutch football clubs because of its notorious history and media seem to use every opportunity to put us in a bad light because of it.
And dont get me wrong Feyenoord definitely is affilliated with hooliganism, which is something you will find with most big clubs. But even if it were Feyenoord-fans, which it werent, dont judge/generalize a whole club and its supporters because of a few lunatics that use Football as an excuse to start a fight. Thank you.