Mankato residents are cleaning up following a weekend riot. A crowd of about three thousand erupted into violence near Minnesota State University following the school's homecoming football game Saturday night. People threw bottles, tore down signs and fences, broke windows and overturned cars. Dozens were arrested in the melee. Daniel Myers is a professor of sociology at the University of Notre Dame and has spent years studying collective violence. He says people tend to congregate after sporting events, and he says this fosters an environment that makes it easier for people to riot.