A crowd that gathered to protest a white supremacists' march Saturday turned violent, throwing baseball-sized rocks at police and vandalizing vehicles. Six people were arrested and police, fire and media vehicles were damaged, Police Chief Mike Navarre said. At least two dozen members of the Roanoke, Virginia-based National Socialist Movement, which calls itself "America's Nazi Party," gathered at a city park to march under police protection. Organizers said they were demonstrating against black gangs that were harassing white residents. The march was canceled, and the violence broke out about a quarter mile away from the park along the planned route. Keith White, a black resident, criticized city officials for initially allowing the march. "They let them come here and expect this not to happen?" said White, 29. Two hours after authorities called off the march, 150 officers continued to chase bands of youths.