At least six groups have issued warnings about the false rumors, including some pleading with the public to stop sharing the misinformation.

“Rumors spread just like wildfire and now our 9-1-1 dispatchers and professional staff are being overrun with requests for information and inquiries on an UNTRUE rumor that 6 Antifa members have been arrested for setting fires in DOUGLAS COUNTY, OREGON,” the Douglas County Sheriff's Office wrote in a Facebook post on Thursday.

The false claims also became fodder for the now-sizable online QAnon community, which began amplifying various false reports earlier in the week.

The sheriffs in Jackson County, Oregon, and Mason County, Washington, posted similar warnings, begging locals to stop spreading unsubstantiated claims.

A firefighters union in Washington state called Facebook “an absolute cesspool of misinformation right now,” in a post that sought to quell more rumors about the fires’ origins.

On Friday afternoon, the FBI's Portland field office tweeted that reports about "extremists" setting wildfires were untrue.

The Medford police debunked the antifa rumor along with a separate, less viral false claim that the fires were a result of arson by the Proud Boys, a far-right group whose members describe themselves as “western chauvinists” and have been an antagonistic mainstay of Black Lives Matter protests.

A fire in Ashland, Oregon, is being investigated as arson, but The Oregonian reported Ashland Police Chief Tighe O’Meara as saying, “One thing I can say is that the rumor it was set by Antifa is 100% false information.”

Despite protestations from law enforcement, rumors have spread through far-right Facebook groups and news websites like Gateway Pundit and the Post Millennial in stories alleging without evidence that Jeff Acord, a 36-year-old man arrested on charges of starting a fire in Puyallup, Washington, was an “antifa militant.” The Post Millennial later changed the story to call Acord a “BLM activist.”

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