MINNEAPOLIS (AP) - FBI officials said on Monday that they foiled a terrorist attack that was being planned in a small western Minnesota town.
But they offered no details about the exact targets of the attack - or the motive of the man accused of having a cache of explosives and weapons in a mobile home.
The FBI said "the lives of several local residents were potentially saved" with the arrest of Buford Rogers, 24, who made his first appearance on Monday in US District Court in St. Paul on one count of being a felon in possession of a firearm.
Rogers, of Montevideo, was arrested on Friday after authorities searched a mobile home he's associated with and found Molotov cocktails, suspected pipe bombs and firearms, according to a court affidavit.
"The FBI believed there was a terror attack in its planning stages, and we believe there would have been a localized terror attack, and that's why law enforcement moved quickly to execute the search warrant on Friday to arrest Mr. Rogers," FBI spokesman Kyle Loven said on Monday.
He said the investigation is ongoing, and agents are looking at the case as one of domestic terrorism.
Mr Loven said the investigation prohibits him from getting into details about Rogers' target, or his possible political or religious views, but he said the FBI is confident in calling this a "terror" situation. He also said the alleged target was believed to be in Montevideo, a city of about 5,000 people about 210 kilometres west of Minneapolis.
"We had information which indicated that Mr Rogers was involved in a plot to conduct terror activities in and around the Montevideo area," he said. He declined to say whether Rogers was believed to be acting alone or as part of a group, or if other arrests were expected.
Montevideo Police Chief Adam Christopher said a homemade sign in front of the mobile home that bore the letters "BSM" refers to a local anti-government militia group called the Black Snake Militia, which the Rogers family started.
"That is not a large scale, nationwide group, as far as I know," Mr Christopher said. "I think it's kind of them, and their family, and a few of their friends."
Mr Mark Pitcavage, who researches militias for the Anti-Defamation League, said the Black Snake Militia is a movement that has slowly grown from about 50 active groups around the US a few years ago to more than 260 small groups today.
Mr Pitcavage said there are "a whole lot of little militia cells out there with 6-8 people in there, which is what this seems to be. ... It's teeny tiny, it's probably a group of like-minded friends who believe some of the same things."
Rogers' father, Jeff Rogers, told KMSP-TV his son doesn't own any guns, and the guns in the home belonged to him. He said his son is not a terrorist.
"He was not out to bomb nobody and I have no clue where the hell that came from," Jeff Rogers said. "I have no idea of who the hell he'd even be targeting. He's not that kind of a person. I can guarantee you that."
Rogers appeared in court Monday wearing a construction company T-shirt, baggy pants, and work boots. He answered "yes sir" and "no sir" to questions from US Magistrate Tony Leung, who ordered him held pending a detention hearing Wednesday, citing "serious concerns."
Rogers was appointed a federal defender, but an attorney was not immediately assigned. Defendants do not typically enter pleas during initial appearances and he made no statement about the case to the court.
In a news release on Monday, the FBI said the alleged terror plot was discovered through analysis of intelligence gathered by local, state and federal authorities.
"Cooperation between the FBI and its federal, state, and local partners enabled law enforcement to prevent a potential tragedy in Montevideo," Mr Christopher Warrener, the special agent in charge of the FBI office in Minneapolis, said in the statement.
According to a federal affidavit, FBI agents from the domestic terrorism squad searched the mobile home in Montevideo and discovered Molotov cocktails, suspected pipe bombs and firearms. The affidavit said Buford was there at the time, and one firearm recovered from the residence was a Romanian AKM assault rifle.
In an interview with authorities, Rogers admitted firing the weapon on two separate occasions at a gun range in Granite Falls, the affidavit said. Rogers has a 2011 conviction for felony burglary and is not allowed to have a firearm.