Flash crowds in high schools

From an NPR interview with Principal Ed Kovochich, who has banned cell phones in his Milwaukee high school because they’ve been causing flash crowds at what would otherwise have been a simple one-on-one fight:

Quite a bit of the school was text messaged where the fight was taking place, and soon there were hundreds, and they were cheering and jeering and usually you get into that mob violence mentality. And suddenly what was 3-on-1 became 3-on-2 and then 3-on-3 and etc. and before you knew it we had a lot of kids fighting.