The FBI is quoted in police documents as saying that the far-right men's group called the Proud Boys is an "extremist group with ties to white nationalism," according to documents first reported by The Guardian.

The Guardian's report uncovers an internal affairs review involving a Clark County Sheriff's deputy who was fired for her affiliation with the Proud Boys. In that review document, the Clark County Sheriff's Office—located in Southwest Washington state—refers to an FBI classification of the Proud Boys as an extremist group.

The Sheriff's Office also warns that the local field office has been monitoring recruiting efforts in the Pacific Northwest.

"The FBI has warned local law enforcement agencies that the Proud Boys are actively recruiting in the Pacific Northwest and that some Proud Boys members have contributed to the recent escalation of violence at political rallies held on college campuses, and in cities like Charlottesville, Virginia, Portland, Oregon and Seattle, Washington," the report says. "Internal Affairs reviewed numerous documents, videos and open source publications related to the evolution of the Proud Boys from a 'men's social club' to 'alt-right fight club' to a designated 'extremist group', as defined by the FBI."

The Proud Boys have been called a hate group by the Southern Poverty Law Center. The self-identified "western chauvinists" frequently reject being labeled as part of the alt-right, but Proud Boys often show strong affinities for white nationalism, xenophobia and anti-Muslim rhetoric.

Portland has seen violence at marches attended by Proud Boys associated with Vancouver, Wash.-based right-wing protest group Patriot Prayer. The membership of these two groups sometimes overlaps, and both organizations see Portland as a city where they can battle antifascists, or Antifa.

A small group of Proud Boys rallied in Portland on Nov. 17, but the event largely avoided the brutal violence that has unfolded at several past rallies.