I went to a River Plate game here because, well, you have to when in Argentina. It was the craziest thing I've ever seen. The opponent's section was fenced off with barbed wire and policemen with sub machine guns. When the game was over (RP won), the opponent section was allowed to leave first, AND THEN the rest of the stadium once they got their head start. The stands looked like they were alive with fans jumping up and down. It was truly something you don't see in the States.