IDAHO (NYTIMES) - Dozens of members of a white supremacist group were arrested Saturday (June 11) in Idaho before they could act on plans to riot at a local Pride event, police said.

After receiving a tip from a concerned citizen, police detained and charged 31 people who belonged to a far-right group known as Patriot Front, said Mr Lee White, the chief of the Coeur d'Alene Police Department, at a news conference.

They are being charged with conspiracy to riot, a misdemeanour, he said.

Mr Bob Norris, the sheriff of Kootenai County, said that a person reported seeing a group of people jump into a van near the intersection of Northwest Boulevard and Interstate 90 in Coeur d'Alene.

"And they were all dressed like a small army," Norris said. "We had units in their area, and we were able to intercept them pretty quickly."

A few miles away, the North Idaho Pride Alliance was holding Pride in the Park, an annual event, at Coeur d'Alene City Park.

The Anti-Defamation League (ADL), which tracks extremist organisations and hate crimes, describes Patriot Front as a Texas-based white supremacist group that formed when members of another white supremacist group, Vanguard America, broke off after the Unite the Right rally in Charlottesville, Virginia, in 2017.

The members arrested had come to Idaho from several states, police said, including Texas, Utah, Colorado, South Dakota, Illinois, Wyoming, Washington, Oregon and Virginia. At least one of the members lived in Idaho, authorities said.

According to the ADL, Patriot Front frequently participates in "flash demonstrations," which are designed to create viral video content and for which members generally wear masks and "khaki pants and a blue or white polo shirt," and sometimes employ smoke bombs.

White said those arrested were wearing khaki pants as well as arm patches and hats emblazoned with Patriot Front logos. Videos of the arrest circulating on social media show men on their knees with their hands tied behind them. Many of the men are masked and wearing blue shirts.

"If you go online, look up 'Patriot Front,' that's exactly how these individuals are dressed," Mr White said.

Many of the men also had shields and wore shin guards, and police recovered one smoke grenade, they said. They did not mention other weapons.

"I have no doubt in my mind, they were coming downtown to riot," Mr White said.

Mr White denied online rumours claiming that the arrests had stemmed from the work of informants.

"This all came from a concerned citizen," he said.

An apparent leader of the group had a seven-page document outlining an operational plan in extensive detail, the chief said.

After pulling up a digital image of the document, White read brief selections to The New York Times that detailed how smoke was to be used: "A column forming on the outside of the park, proceeding inward, until barriers to approach are met" and "once an appropriate amount of confrontational dynamic has been established the column will disengage and head to Sherman".

Sherman Avenue runs through the centre of downtown Coeur d'Alene.

Kootenai County jail records revealed that Thomas Rousseau, the founder of Patriot Front, was among those booked on criminal conspiracy charges.

In the weeks leading up to the Pride event, Mr Norris said, "there was a lot of chatter going on" from both far-right and far-left sources about potential confrontations at the gathering.

Some of that came from local groups, including the Panhandle Patriots, a far-right motorcycle club in northern Idaho. But several of those groups publicly altered their plans as worries of a violent confrontation increased.

The Panhandle Patriots rebranded a planned Gun d'Alene anniversary event as a North Idaho Day of Prayer.

Mr White said that, at this point, he did not have information suggesting that local members of the alt-right or of other far-right groups were connected to Patriot Front's plans.

Mr White said there were members of antifa groups present at the Pride event. But the Pride in the Park attendees "felt relatively safe, at least the event organisers did," Mr White said.

"There were people walking around the event with long guns and handguns and bear spray and all kinds of things like that," he said. But, he added, "that is legal in Idaho".

The action in Coeur d'Alene was not the only threat that involved a far-right group and an LGBTQ event Saturday. In San Lorenzo, California, members of the Proud Boys disrupted the Drag Queen Story Hour, a reading event at the San Lorenzo Library that was attended by children, parents and other community members, the Alameda County Sheriff's Office said on Facebook.

The men shouted homophobic and transphobic slurs at the event organiser and were described as having a violent demeanour, authorities said.

Deputies arrived and de-escalated the situation, but a hate crime investigation is underway, the sheriff's office said.