BURNS, Ore., Jan. 4 (UPI) -- The FBI is leading an investigation into the armed siege of the Malheur National Wildlife Refuge headquarters to protest the prosecution of two ranchers.
"The FBI is working with the Harney County Sheriff's Office, Oregon State Police and other local and state law enforcement agencies to bring a peaceful resolution to the situation at the Malheur National Wildlife Refuge," the FBI's Portland office said. "Due to safety considerations for both those inside the refuge as well as the law enforcement officers involved, we will not be releasing any specifics with regards to the law enforcement response."
Nearby Harney County School District 3 canceled classes for the week.
The group, of an undisclosed number, believed to be armed, took control of the unoccupied building Saturday after holding a rally in support of two ranchers convicted of arson.
The group said it was prepared to stay for years and to use violence if authorities attempt to evict them.
"These men came to Harney County claiming to be part of militia groups supporting local ranchers, when in reality these men had alternative motives to attempt to overthrow the county and federal government in hopes to spark a movement across the United States," Sheriff David Ward said in a statement.
The incident began in the town of Burns, where protesters were voicing support for Dwight Hammond, 73, and his son Steven, 46, who were convicted of arson in 2012 and served time in prison but whose sentences a court later ruled were too short. Dwight and Steven Hammond were originally sentenced to three years and one year, respectively.
The men are scheduled to turn themselves in on Monday to serve five years in prison. Dwight Hammond previously said he and his son are planning to peacefully report to prison despite the protest. There was no police presence at the building Monday morning.
The Hammond family has distanced itself from the group and its leader, Ammon Bundy -- the son of Cliven Bundy, a Nevada rancher who gained international attention in 2014 after staging an armed standoff with federal authorities over a grazing dispute with the Bureau of Land Management.
"Neither Ammon Bundy nor anyone within his group/organization speak for the Hammond family," the Hammonds' attorney, W. Alan Schroeder, wrote to Ward.
The BLM district office in Burns, Oregon, is closed until further notice.— BLM Oregon (@BLMOregon) January 4, 2016
In a blog post written ahead of the takeover, Ammon Bundy said his grievances with the federal government are based on land seizures that harm working-class farmers.
"The abuses and corruptions affecting people like the Hammonds are symptoms of a more encompassing problem. Government employees (full-time & elected) have changed their culture from one of service to, and respect for the people, to the roll of being a masters," Bundy wrote. "On the subject of the land, it is evident that government employees are no longer assisting the people in claiming, using and defending property. Instead, they have become the people's competitor to the benefits of the land, and are willing to use force on those who they erroneously compete against."
In the arson case, the Hammonds said they lit the fires to reduce the growth of invasive species and protect their land from wildfires.
The acting U.S. Attorney Billy J. Williams of Oregon wrote an opinion piece in the Burns Times Herald in December defending the prosecution's actions in the Hammond case.
"Five years ago, a federal grand jury charged Dwight and Steven Hammond with committing arson on public lands and endangering firefighters," Williams wrote. "Steven Hammond was also found guilty of committing a second arson in 2006."
Prosecutors said witnesses saw the Hammonds illegally slaughter at least seven deer on public land, with some "limping or running from the scene."
Williams wrote that a teenage relative of the Hammonds testified that Steven Hammond gave him a box of matches and told him to start a fire, which "destroyed evidence of the deer slaughter and took about 130 acres of public land out of public use for two years."
Ammon Bundy told CNN that the group's actions are about "taking the correct stand without harming anybody to restore the land and resources to the people so people across the country can begin thriving again."
"We will be here as long as it takes," he added. "We have no intentions of using force upon anyone, [but] if force is used against us, we would defend ourselves."