The FBI has arrested two alleged members of the far-right anti-government group the Boogaloo Boys, as authorities express increasing concern about the potential for violence around next week’s US midterm elections.

Timothy Teagan was expected to appear on Wednesday in federal court in Detroit, where charges against him would be unsealed, an FBI spokesperson said.

In a criminal complaint filed on Monday, the FBI said there was enough evidence to charge Aron McKillips, of Sandusky, Ohio, with illegal possession of a machine gun and the interstate communication of threats. The complaint said McKillips was a member of the Boogaloo Boys and was believed to be in a militia group called the Sons of Liberty.

McKillips’s lawyer, Neil McElroy, said he had asked for McKillips to be released pending a 9 November detention hearing in Toledo.

Teagan’s arrest on Tuesday came a week before election day. Election workers have been targeted by threats and harassment since the 2020 election, which Donald Trump has refused to admit he lost.

Federal authorities have charged at least five people already this year. Election officials are concerned about conspiracy theorists signing up to work as poll watchers. Some groups that have trafficked in lies about the 2020 election are recruiting and training watchers.

In Phoenix on Tuesday, a federal judge agreed to put limits on a group monitoring outdoor ballot drop boxes in Arizona.

The US district court judge, Michael Liburdi, said he would issue a temporary restraining order against Clean Elections USA and also the Lions of Liberty and the Yavapai County Preparedness team, which are associated with the far-right anti-government Oath Keepers group.

Those groups or anyone working with them will be barred from filming or following anyone within 75ft (23 metres) of a ballot drop box or the entrance to a building that houses one. They cannot speak to or yell at individuals within that perimeter unless spoken to first. It is the standard distance maintained around polling sites under Arizona law, but it has typically never applied to drop boxes.

The order also prohibited members of the groups or agents working on their behalf from carrying firearms or wearing body armor within 250ft (76 metres) of a drop box.

In Michigan, Teagan was among a dozen or so people who openly carried guns while demonstrating in January 2021 outside the state capitol in Lansing. Some promoted the “boogaloo” movement, a slang term that refers to a second US civil war.

Teagan told reporters the purpose of the demonstration was “to urge a message of peace and unity to the left and right, to the members of [Black Lives Matter], to Trump supporters to Three Percenter militias to antifa”.

Some boogaloo promoters insist they aren’t genuinely advocating for violence. But the movement has been linked to domestic terrorism plots.

In the criminal complaint against McKillips, the FBI alleges that he made online threats including one to kill a police officer and another to kill anyone he determined to be a federal informant. The FBI also contends that McKillips provided equipment to convert rifles into machine guns.

“I literally handed out machine guns in Michigan,” McKillips said in a recording, the complaint states.

In September 2021, he said in a private chat group: “Ain’t got a federal badge off a corpse yet, so my time here ain’t near done yet lol.”

In May this year, McKillips and another user in the Signal messaging system threatened to kill a different user in the belief the person was an informant for the FBI or Bureau of Alcohol, Tobacco, Firearms and Explosives, the complaint says.

In July, McKillips threatened in a Signal group to “smoke a hog”, meaning kill a police officer, if conditions worsened following a fatal police shooting in Akron, it says.

McKillips frequently advocated violence against police officers, federal agents, government buildings and stores like Walmart and Target, and even threatened to blow up Facebook headquarters, the complaint says.