A group of men who call themselves the “Oath Keepers” arrived in Ferguson, Missouri, late Monday night, armed with assault rifles and decked out in military fatigues.

Their arrival came during a night of tension in the St. Louis suburb, as police and protesters once again stood toe-to-toe in Ferguson and small clashes broke out.

Peaceful demonstrations on Sunday to mark the one-year anniversary of the death of 18-year-old Michael Brown, an unarmed black teenager shot and killed by a Ferguson police officer, devolved into violence Sunday night.

On Monday, protesters once again took to the streets. Late at night, the right-wing armed group arrived.

St. Louis County Police Chief Jon Belmar called their presence “both unnecessary and inflammatory,” according to NBC News.

Journalists and activists at the scene posted photos of the group standing on West Florissant Avenue, the center of the recent protests in Ferguson. It is legal to open carry these types of rifles in the state of Missouri. According to state law, people who have a valid gun permit can “openly display the firearm… unless the firearm is intentionally displayed in an angry or threatening manner.”

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