A few days ago, Ammon Bundy wrote a Facebook post urging people to pray for the Hammonds, two Oregon ranchers facing prison time for arson.

On Saturday, Bundy went further. He and an unknown number of other individuals, armed with guns, stormed an empty building in a federal wildlife refuge in Oregon in support of the ranchers. The federal government, Bundy said, was unfairly punishing Dwight Hammond, 73, and his son Steven Hammond, 43, who were convicted in 2012 of committing arson on public lands in 2001.

“We will be here as long as it takes,” Bundy said in an interview posted on the Bundy Ranch’s Facebook page late Saturday night.

Bundy and the armed protesters took over the headquarters of the Malheur Wildlife Refuge, which was closed for the holiday weekend, after participating in a peaceful rally in Burns, Oregon, in support of the Hammonds. Bundy said that the property, which is managed by the U.S. Fish and Wildlife Service, is “owned by the people, and it has been provided to us to be able to come together and unite to make a hard stand against [government] overreach.”

When the Hammonds were originally sentenced, they argued that the ​minimum mandatory sentence for arson on federal land—five years—was unconstitutional, according to the U.S. district attorney’s office in Oregon. The trial court agreed and reduced the sentence. But an appeals court eventually upheld the federal law, and a judge imposed the mandatory sentence last October, with credit for time the Hammonds already served. The father served three months, while the son, who was also found guilty of committing arson on public lands in 2006, served one year, according to the Associated Press.

The Hammonds claimed they set fire to the lands, which they leased from the government for grazing cattle, to fight off invasive species. They are expected to report to prison on Monday.

The Hammonds’ lawyer wrote to the sheriff of Harney County, Oregon, Dave Ward, on Friday that “neither Ammon Bundy nor anyone within his group/organization speak for the Hammond family,” according to the AP.

Bundy has insisted that the armed protesters at the refuge were being peaceful and urged “all freedom-loving people” to join their cause. The protesters demand that the Hammonds be released. But Bundy told CNN Sunday that “if force is used against us, we would defend ourselves.”

Bundy is the son of Nevada rancher Cliven Bundy, who is known for staging his own standoff against the federal government. In April 2014, Cliven, along with dozens of armed supporters, chased away Bureau of Land Management rangers who attempted to confiscate Bundy’s cattle herd, which had illegally grazed on federal land since 1993.

The elder Bundy appeared to distance himself from his son’s standoff, telling Oregon Public Broadcasting’s John Sepulvado on Saturday that the standoff was “not exactly what I thought should happen.”

The county sheriff’s office has advised people to stay away from the refuge as the standoff continues, according to The Oregonian.