An Oregon sheriff accused members of a small, armed group occupying a national wildlife refuge of attempting to intimidate federal employees and law enforcement officers.

Harney County Sheriff Dave Ward told a community meeting Monday night that officers and U.S. Fish and Wildlife employees have reported being followed to their homes and observed while inside and that self-identified "militia members" have tried to engage them in debates about their status as federal employees.

Ward said law enforcement at every level "will not be intimidated from doing their jobs", telling community members, "there's an hour glass and it's running out," The Oregonian reported.

The U.S. Fish and Wildlife Service administers the Malheur National Wildlife Refuge, which has been occupied since Jan. 2. 

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

Also Monday, protest leader Ammon Bundy told reporters he and his followers are going through government documents stored inside refuge buildings. Bundy said the documents would "expose" how the government has discriminated against 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 protest that led to the occupation.

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

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.

Fish and Wildlife 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," the agency said in a statement. "Any movement of cattle onto the Refuge or other activities that are not specifically authorized by USFWS constitutes trespassing."

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.

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

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.

The Associated Press contributed to this report.