The Hammerskin Nation's planned series of concerts has raised concern with police and the city of Boise, even though the festival's exact venue isn't known. An online poster for the event simply names Boise as the event's location on Oct. 6.

Also unclear is why the Hammerskins chose the Treasure Valley.

The Southern Poverty Law Center, which tracks hate groups across the country, calls the Hammerskin Nation "one of the oldest, most violent and most dominant skinhead groups in the United States." The center identifies Wade Michael Page, who in August opened fire at a Sikh temple in Wisconsin, killing six, as a member of the organization.

Efforts to contact members of the Hammerskin Nation were unsuccessful.