Authorities have been on alert since advertisements for Hammerfest 2012 near Boise surfaced online, said Sgt. Jeff Basterrechea, who is with the police department’s gang intelligence unit. The white supremacist group Hammerskin Nation plans to hold the event Oct. 6, according to the flier circulating online.

“This is a very high priority,” Basterrechea said. “The mayor’s office has received numerous complaints about this.”

The skinhead group is rooted in Texas and has branches in Australia and Canada, according to the SITE Monitoring Service, a private intelligence firm that searches the Internet for extremist activity. The gunman who killed six worshippers at a Sikh temple in Wisconsin last month described himself as a member.

The group has not disclosed the exact location of the planned Idaho event and attempts to contact local Hammerskin chapters were unsuccessful, KTVB-TV reported. Police are working with local venues to make them aware of the group, Basterrechea said.

Former neo-Nazi skinhead Marine T.J. Leyden told the news station he previously recruited for the group with events like Hammerfest. Leyden, who famously left the movement in 1996 and has promoted tolerance ever since, said the Boise event will be used to boost the group’s numbers.

“They’re going to say, ‘Hey, come to this show.’ These kids are going to see it, they’re going to get all pumped up, they’re going to think it’s fantastic,” said Leyden, who cautioned that protesters should stay away and allow law enforcement to monitor the event.

“The group is extremely violent. The Hammerfests that they throw in different parts of the country are designed for a couple things. One it’s designed for unity, but it’s also designed to get people’s anxiety up,” Leyden said.

“My best suggestion is let law enforcement handle these guys. Don’t go out and counter-protest. This is what they want. They want counter-protesters yelling, screaming and hollering out there to make them feel like they’re big, tough men.”

In 2009, the Homeland Security Department issued several reports on individual foreign and domestic extremist groups such as al-Qaida and Hammerskin Nation. The Hammerskin assessment said many of the group’s members received military training and fought in Iraq and Afghanistan.