BURNS, Ore. -- The leader of a small, armed group occupying a national wildlife refuge in southeastern Oregon said Monday he and his followers are going through government documents stored inside refuge buildings.

Ammon Bundy told reporters the documents will be used to "expose" how the government has discriminated local ranchers who use federal land for cattle grazing.

Bundy said the documents would also help secure the release of Steven and Dwight Hammond, two area ranchers convicted of arson who returned to prison last week to serve longer sentences. The Hammonds' case set off the occupation of the Burns-area refuge on Jan. 2.

Bundy said his group is not accessing government computers at the Malheur National Wildlife Refuge, including personnel files.

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After the news conference, the group drove in a convoy to a ranch near the refuge and tore down a stretch of government-erected fence. The goal, according to the armed men, was to give the rancher access to the range that had been blocked for years. It's not clear where the fence was located or which rancher sought the group's help.

The refuge is administered by the U.S. Fish and Wildlife Service. Spokesman Jason Holm said because the documents and files at the refuge may have personally identifiable information, the agency "is taking necessary steps to ensure employee and family safety."

The agency strongly condemned the destruction of the fence and said the action undermines hard-earned conservation impacts achieved in the area.

"Removing fences, damaging any Refuge property, or unauthorized use of equipment would be additional unlawful actions by the illegal occupiers," Fish and Wildlife said in a statement. "Any movement of cattle onto the Refuge or other activities that are not specifically authorized by USFWS constitutes trespassing."

Sixteen full time employees and one part time employee usually work at the refuge, Holm said. Some who can't work away from the refuge have taken administrative leave, while others are working from home or another office.

In Burns, about 30 miles from the refuge, schools reopened after being canceled for a week over safety concerns due to the refuge standoff.

Government offices in the area remained closed, including those of the Bureau of Land Management. BLM spokesman Randy Eardley said about 60 BLM employees were working from home.

"There is a very clear threat to BLM employees," Eardley said, but he did not cite any specific threats.

Ammon Bundy called his group's occupation of the refuge "peaceful" and said the armed men would not leave until the Hammonds are out of prison and abuses against ranchers are exposed. Bundy called the occupation a "moral and righteous stand for the future of this country."

Dwight Hammond, 73, and Steven Hammond, 46, said they lit the fires in 2001 and 2006 to reduce the growth of invasive plants and protect their property from wildfires.

"Remember: It's not about me, it's about America and somehow we have to get the wheels back on this wagon because they are flying off," Dwight Hammond told CBS affiliate KOIN previously. He said then he felt his upcoming prison term was a life sentence.

"I'm not very happy about that. Just don't know what to say," Hammond said. "It just seems like a little overreach for having burned 127 acres."

The two were convicted of the arsons three years ago and served time -- the father three months, the son one year. But a judge ruled their terms were too short under federal law and ordered them back to prison for about four years each.

The decision has generated controversy in a remote part of the state.

A man representing hunters and anglers, who arrived in Oregon from New Mexico this weekend, condemned the Bundy group at the news conference.

"What I see is a lunatic fringe of extremists who have taken my land over," said New Mexico Wildlife Federation executive director Garrett VeneKlasen. The group represents sportsmen, including hunters and anglers.

Bob Sallinger, conservation director of the Audubon Society of Portland, said in a statement last week that occupation of the refuge "holds hostage public lands and public resources to serve the very narrow political agenda of the occupiers."

Federal, state and local law enforcement officials are monitoring the occupation but have not taken any action.

The county sheriff and many locals have asked that Bundy and his group leave. But Bundy says he is not ready to go.

Ammon Bundy is a son of Cliven Bundy, a Nevada rancher who was at the center of a tense standoff with federal officials in 2014 over unpaid grazing fees.

Local residents have mixed feelings about the occupation. Just three miles from the refuge, rancher Tom Davis and his son Jake continue the hard work of raising cattle on the high desert.

"I think it's probably time for these guys to go home and I just pray that nothing will really happen to them," Tom David told CBS News.

"As long as they don't get violent, I think it's good coverage," his son added.

Good coverage, he says, for the challenges ranchers face across the West, where so much land is controlled by the federal government.