A group of armed extremists, including three of Nevada rancher Cliven Bundy’s sons, occupied the headquarters of a national wildlife refuge in Oregon Saturday night in a standoff to protest the imprisonment of two Oregon ranchers accused of arson.

"We're planning on staying here for years, absolutely," Ammon Bundy, one of the occupiers, who refer to themselves as “militiamen,” told the Oregonian newspaper.

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The occupation came after several hundred demonstrators marched through Burns, Oregon, to protest against the pending imprisonment of father and son Harney County ranchers Dwight Hammond Jr. and Steven Hammond, who a federal court decided must return to prison after their time served for setting fires on public land to protect their property from wildfires was deemed insufficient.

Bundy said feds' actions are violation of constitution. Founding fathers were ready to die, and so are they. #OregonUnderAttack

— Ian Kullgren (@IanKullgren) January 3, 2016

The number of militiamen holed up at the site has not been confirmed. Early estimations believed there to be 150: reporters who have visited the center claim the number is more like 15.

Feels like it's worth repeating: Every reporter who's visited Malheur says there are, at most, 15 militia guys holed up. Stop saying 150.

— Aaron Mesh (@AaronMesh) January 3, 2016

Ammon Bundy would not confirm how many people are at the refuge because of "operational security" #Oregon

— Ryan Haas (@ryanjhaas) January 3, 2016

The sit-in of military uniform-clad militias also has wider-reaching aims: to create a U.S.-wide movement to create autonomous zones independent from federal authorities.

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“We’re going to be freeing these lands up, and getting ranchers back to ranching, getting the loggers back to logging, getting the miners back to mining where they could do it under the protection of the people and not be afraid of this tyranny that’s been set upon them,” Bundy said, in a separate video posted on Facebook.

Bundy told reporters that the occupiers were not out to hurt people, but could resort to violence if police moved in on them. Bundy’s brother Ryan reportedly told Oregonian reporter, Ian Kullgren, that the group is “willing to kill and be killed if necessary.”

I talked to Ryan Bundy on the phone again. He said they're willing to kill and be killed if necessary. #OregonUnderAttack

— Ian Kullgren (@IanKullgren) January 3, 2016

2 Bundys said they're not planning on attacking unless they're attacked. Said they want to start a movement. #Oregonstandoff

— Ian Kullgren (@IanKullgren) January 3, 2016

“It doesn’t have to stop here. This could be a hope that spreads through the whole country, the whole United States. Everybody’s looking for this hope because the government has beat us, and oppressed us, and took everything from us; they will not stop until we tell them no,” armed occupier, Blane Cooper, said.

Local journalists report that authorities have begun to address the situation. 

"A collective effort from multiple agencies is currently working on a solution," Sheriff Dave Ward is reported to have said.

MILITIA UPDATE: Sheriff Dave Ward: "A collective effort from multiple agencies is currently working on a solution."

— Les Zaitz (@LesZaitz) January 3, 2016

The Bundy family have been involved in anti-federal law standoffs in the past. In 2014, the family’s ranch was the base of an armed demonstration against the U.S. Bureau of Land Management.

Authorities eventually gave in to the Bundy’s demands, after the father, Cliven Bundy, refused to pay grazing fees for his cattle.  

U.S. citizens took to Twitter to express their outrage that authorities had not moved in on the armed protesters, while unarmed Black people were routinely shot dead by police and innocent Muslims labeled as terrorists.

Best photo I've seen all night. #OregonUnderAttack pic.twitter.com/GUDM2G6zqo

— Smooth Kobra (@smoothkobra) January 3, 2016

So would #OregonUnderAttack already be over if the militia involved were 12 & had toy guns, or ... is something different here?

— morrigan disapproves (@meli_lewis) January 3, 2016

Let's interrogate families of the #OregonUnderAttack militiamen and spy on their places of worship. Then I remembered: nah, they're white.

— omid safi (@ostadjaan) January 3, 2016

I'm tired of seeing radical white men do whatever they want without facing any sort of backlash from police or the media. #OregonUnderAttack

— عمر فلسطين (@WeTeachLifeSir_) January 3, 2016

Men with REAL weapons are being negotiated with, while #TamirRice, a young boy with a fake gun was shot right away...? #OregonUnderAttack

— keshika (@BADLANDprincess) January 3, 2016

These are just bad headlines #Oregon pic.twitter.com/LKnECOWO9R

— Sana Saeed (@SanaSaeed) January 3, 2016

Can you imagine if 150 armed Black people took over a federal building? Or 150 armed Muslims? This is preposterous.

— Imani Gandy (@AngryBlackLady) January 3, 2016