The fight was between Eagles' fans and the police officers, and it doesn't appear any Vikings' fans were involved. The incident, which required Philadelphia police officers and Pennsylvania State troopers to get under control, left at least one fan beaten and blooded.
Despite the late kickoff, Eagles fans were seen arriving to the stadium to start tailgating as early as 7 a.m. EST on Sunday.
http://www.nj.com/eagles/index.ssf/2018/01/photos_riot_police_on_horses_storm_parking_lots_be.html