Alan Swinney is being charged with assault, attempted assault, menacing, and other crimes, Multnomah County District Attorney Mike Schmidt announced Wednesday.
According to court documents, Swinney allegedly fired a paintball gun on Aug. 15 to cause physical injury to another person and unlawfully discharged mace or a similar substance as well as trying to assault others.
Swinney is accused of again causing physical injury to another person, unlawfully discharging mace or another substance, and pointing a revolver at someone, placing that person in fear of imminent serious physical injury, during a street brawl that involved members of the Proud Boys and Antifa in downtown Portland on Aug. 22.
Police officials said they declined to intervene in the brawl because too many officers had been working during the ongoing, near-nightly riots, leaving too few to be able to insert themselves between the groups.
A Proud Boys rally and a counter-demonstration on Sept. 26 went more smoothly after Oregon Gov. Kate Brown declared an emergency and sent state troopers to Portland.
Swinney was arrested on Wednesday and is scheduled to be arraigned on Thursday. It wasn't clear whether he had a lawyer.
Proud Boys is a group of "Western Chauvinists" that says it advocates for the Second Amendment, closed borders, and minimal government. Members have been involved in violent clashes with Antifa, a far-left, anarcho-communist group, in several cities in the past.
On Tuesday, Swinney posted on Twitter asking for donations.
"Help me fight these people. Please like and retweet. Every retweet makes a terrorist lose his or her mind," he wrote.
The fundraiser page said Swinney has been going to rallies for President Donald Trump since August 2018 and been targeted by Black Lives Matter and Antifa.
"I am being prosecuted today because I didnt allow left-wing terrorists to attack me and others at the rally," he claimed.