Dozens of members of a white supremacist group have been arrested after police in Idaho received a tip they were making preparations like “a little army” ahead of a Pride event at the weekend.

The 31 Patriot Front members were arrested after they were spotted loading riot gear into a U-Haul vehicle at a hotel car park in Coeur d’Alene.

Among those being held on misdemeanour charges of conspiracy to riot was Thomas Ryan Rousseau of Grapevine, Texas, who has been identified by the Southern Poverty Law Centre as the 23-year-old who founded the group after the deadly “Unite the Right” rally in Charlottesville, Virginia, in 2017.

Also among those held was Mitchell F Wagner, 24, of Florissant, Missouri, who was previously charged with defacing a mural of famous black Americans on a college campus in St Louis last year.

Police found riot gear, one smoke grenade, shin guards and shields inside the van after pulling it over near a park where the North Idaho Pride Alliance was holding a Pride in the Park event, Coeur d’Alene Police Chief Lee White said.

The group came to riot around the small northern Idaho city wearing Patriot Front patches and logos on their hats and some T-shirts reading “Reclaim America”, according to police and videos of the arrests posted on social media.

Those arrested came from at least 11 states, including Washington, Oregon, Texas, Utah, Colorado, South Dakota, Illinois, Wyoming, Virginia, and Arkansas.

The six-hour Pride event went on as scheduled, including booths, food, live music, a drag show and a march of more than 50 people, the Idaho Statesman reported.

Michael Kielty, Wagner’s lawyer, said that he had not been provided information about the charges.

He said Patriot Front did not have a reputation for violence and that the case could be a First Amendment issue.

“Even if you don’t like the speech, they have the right to make it,” he said.

Patriot Front is a white supremacist neo-Nazi group whose members perceive black Americans, Jews and LGBTQ people as enemies, according to Jon Lewis, a George Washington University researcher who specialises in homegrown violent extremism.

Mr Lewis said the group’s tactics involves identifying local grievances to exploit, organising on platforms like the messaging app Telegram and ultimately showing up to events marching in neat columns, in blue- or white-collared-shirt uniforms, in a display of strength.

Though Pride celebrations have long been picketed by counter-protesters citing religious objections, they have not historically been a major focus for armed extremist groups.

Mr Lewis said anti-LGBTQ rhetoric has increasingly become a potent rallying cry in the far-right online ecosystem.

The arrests come amid a surge of charged rhetoric around LGBTQ issues and a wave of state legislation aimed at transgender youth, said John McCrostie, the first openly gay man elected to the Idaho legislature.

In Boise this week, dozens of Pride flags were stolen from city streets.

“Whenever we are confronted with attacks of hate, we must respond with the message from the community that we embrace all people with all of our differences,” Mr McCrostie said in a text message.

Sunday also marked six years since the mass shooting that killed 49 people at the Orlando LGBTQ club Pulse, said Troy Williams of Equality Utah in Salt Lake City.

“Our nation is growing increasingly polarised, and the result has been tragic and deadly,” he said.