An Oregon rancher and his son are at the center of an armed protest against the federal government by a group of militiamen.

Dwight and Steven Hammond, of Harney County, were convicted three years ago of setting fires on their ranch that burned federal land. The father and son initially were sentenced to short prison terms, but received new sentences in October, leading to an angry reaction from anti-government protesters, including the sons of Nevada rancher Cliven Bundy.

On Saturday, Ammon Bundy, his brother, Ryan, and a group of armed men seized a federal building at the Malheur National Wildlife Refuge in rural eastern Oregon. The men are calling for the Hammonds to be released from their prison sentences, and for the national forest land to be returned to the local residents.

The Hammonds are expected to report to prison Monday.

Here’s what you need to know:

1. They Set Fires in 2001 & 2006 to Protect Their Ranch Lands, But Damaged Federal Property

Protesters supporting the Hammond family. Dwight Hammond and his wife hugging supporters @KTVZ pic.twitter.com/1pIZOay76t — Wanda Moore (@WandaKTVZ) January 2, 2016

Dwight Hammond, 73, and his son, Steven, 46, were convicted by a federal jury in 2012 of using fire to destroy federal property, according to the Oregon U.S. Attorney’s office.

The fires were set on land managed by the U.S. Bureau of Land Management. The Hammonds leased grazing rights for the property from the BLM.

According to prosecutors the 2001 fire was located in the Steens Mountain Cooperative Management and Protection Area. The U.s. Attorney’s Office said:

Witnesses at trial, including a relative of the Hammonds, testified the arson occurred shortly after Steven Hammond and his hunting party illegally slaughtered several deer on BLM property. Jurors were told that Steven Hammond handed out ‘Strike Anywhere’ matches with instructions that they be lit and dropped on the ground because they were going to ‘light up the whole country on fire.’ One witness testified that he barely escaped the eight to ten foot high flames caused by the arson. The fire consumed 139 acres of public land and destroyed all evidence of the game violations. After committing the arson, Steven Hammond called the BLM office in Burns, Oregon and claimed the fire was started on Hammond property to burn off invasive species and had inadvertently burned onto public lands. Dwight and Steven Hammond told one of their relatives to keep his mouth shut and that nobody needed to know about the fire.

Steven Hammond was convicted in the 2006 arson, which occurred in the Malheur National Wildlife Refuge:

An August lightning storm started numerous fires and a burn ban was in effect while BLM firefighters fought those fires. Despite the ban, without permission or notification to BLM, Steven Hammond started several ‘back fires’ in an attempt save the ranch’s winter feed. The fires burned onto public land and were seen by BLM firefighters camped nearby. The firefighters took steps to ensure their safety and reported the arsons.

Hammonds and their supporters claim they were targeted by the Bureau of Land Management.

“This prosecution will have a chilling effect across the West among ranchers and others who rely on federal allotments and permits. It will harm the positive relationship many ranchers and organizations have worked to forge with the bureau, and the hard work that has been done on the range,” the Oregon Farm Bureau said. “It also is hypocritical given BLM’s own harm to the range, which goes without consequence. It is unjust. OFB worked quietly behind the scenes with BLM through the spring and summer. That diligent diplomatic effort was fruitless.”

2. Prosecutors Appealed the Lenient Sentences Given to the Hammonds

Dwight Hammond was initially sentenced to three months in prison, and Steven Hammond to one year. They both served those sentences, but the federal prosecutor appealed, saying the punishment wasn’t severe enough.

According to the U.S. Attorney’s office, the Hammonds argued during their sentencing that the five-year mandatory minimum they faced was unconstitutional, and the trial court agreed. But the Ninth Court of Appeals upheld the federal sentencing law, saying “given the seriousness of arson, the five-year sentence is not grossly disproportionate to the offense.” The Supreme Court rejected the Hammonds case

In October, they were re-sentenced to the five-year mandatory minimum that their convictions each carried, minus the time they already served. That means both men will serve about four years in prison, which Dwight Hammond has called a “death sentence,” for him according to CBS News.

“We all know the devastating effects that are caused by wildfires. Fires intentionally and illegally set on public lands, even those in a remote area, threaten property and residents and endanger firefighters called to battle the blaze,” Oregon U.S. Attorney Billy Williams said in a statement. “Congress sought to ensure that anyone who maliciously damages United States’ property by fire will serve at least 5 years in prison. These sentences are intended to be long enough to deter those like the Hammonds who disregard the law and place fire fighters and others in jeopardy.”

3. Their Case Caught the Attention of Anti-BLM Groups

The Hammonds case sparked the interest of groups that oppose the Bureau of Land Management, including the family of Nevada rancher Cliven Bundy, who led a tense standoff with the BLM and federal authorities in 2014.

A peaceful protest of outsiders and local residents was held near Hammonds home on Saturday. Following that, Ammon and Ryan Bundy and other armed militiamen went to the nearby Malheur National Wildlife Refuge, which was not occupied by federal employees, and seized the land.

Ammon Bundy told The Oregonian, “The facility has been the tool to do all the tyranny that has been placed upon the Hammonds. We’re planning on staying here for years, absolutely. This is not a decision we’ve made at the last minute.”

In a Facebook video, he called for others to come to Oregon.

“Calling all freedom loving people to come to Harney County Oregon, come to the Malhuer Wildlife Refuge. The people are finally getting some good use out of a federal facility,” he said in the caption of the video. In a previous video, Bundy called for “all patriots” to “stand up not stand down” and “come prepared.”

4. The Hammonds Say the Bundy & the Militiamen Do Not Speak for Them

The Hammonds have said the Bundys and other outside protesters do not speak for them.

“Neither Ammon Bundy nor anyone within his group/organization speak for the Hammond Family,” their attorney, W. Alan Schroder, told KOIN.

They have not commented since the takeover of the federal building.

5. The Armed Protesters Have Said They Are Willing to Fight & Die for Their Cause

This is as close as I was allowed to get to the armed militia occupying the Malheur Wildlife Refuge HQ. #burnsoregon pic.twitter.com/DPztu0VsVU — Jason Wilson (@jason_a_w) January 3, 2016

Ryan Bundy told the Oregonian, “The best possible outcome is that the ranchers that have been kicked out of the area, then they will come back and reclaim their land, and the wildlife refuge will be shut down forever and the federal government will relinquish such control,” he said. “What we’re doing is not rebellious. What we’re doing is in accordance with the Constitution, which is the supreme law of the land.”

He said many of the men at the refuge are willing to fight and die to protect the rights of states, counties and individuals to manage local lands.