The FBI exercised Oregon's new "red flag" law to confiscate firearms from a former Marine who allegedly said he would "slaughter" antifa protesters at a demonstration in Portland earlier this month, according to the Oregonian.

In July, Shane Kohfield threatened to kill antifa members who he feared would take up arms against right-wing activists. He made the threats on a loudspeaker while donning a "Make America Great Again" baseball cap with a knife and a copy of his concealed carry permit strapped to both shoulders.

"If antifa gets to the point where they start killing us, I’m going to kill them next," Kohfield said outside of Portland Mayor Ted Wheeler's home. "I’d slaughter them, and I have a detailed plan on how I would wipe out antifa."

FBI's Joint Terrorism Task responded within days to seize all of Kohfield's weapons. Agents cited the red flag law to temporarily confiscate the guns, though Kohfield had not committed a crime.

The law allows law enforcement and family members to ask a judge to issue an "extreme risk protection order" that prohibits certain individuals from owning weapons. The statute's intent is to be proactive to inhibit violence before it can occur, and many states are enacting similar laws as a way to combat the increasing number of mass shootings in the U.S.

Phil Lemman, Oregon’s acting deputy state court administrator, said Kohfield gave up five guns, including an AR-15.

Kohfield was also admitted to a veterans hospital in Portland and spent 20 days there. Though he was not charged with a crime, he was barred from participating in the August protests organized by the far-right group Proud Boys in Portland that drew counterprotests from antifa.

Kohfield told the Oregonian he understood why he was taken to a local hospital and prohibited from attending the protests, but he insisted he did not plan to harm anyone.

"I looked unhinged," Kohfield said. "I looked dangerous and have the training to be dangerous."

The FBI refused to comment on Kohfield's case.

"The Portland Joint Terrorism Task Force’s role is to assess, address and mitigate any given threat against the people of Oregon appropriately," a representative for the FBI's Portland office told the Oregonian on Friday.