The federal government began shutting its offices in eastern Oregon days before the showdown with armed anti-government protesters began this week, because of mounting hostility and security threats, officials said Thursday.

With threats against individual employees and a campaign of intimidation by out-of-town ranchers who had been in the isolated area for weeks, federal officials at agencies from the U.S. Forest Service to the Bureau of Land Management started sending more than 150 people home as early as Dec. 30.

That was three days before a group calling itself Citizens for Constitutional Freedom holed up with guns inside a wildlife sanctuary in remote Harney County to protest the arson conviction of two local cattle ranchers who set fires to federal lands.

Ammon Bundy and a group of armed supporters, including his brother Ryan, were arrested in Ore. on Jan. 26. Here's a look at the Bundy family's history of anti-government actions. (This video was updated on Feb. 11, 2016.) Cliven, Ammon and Ryan Bundy are all under arrest. Here's a look at the Bundy family's history of anti-government actions. (Jenny Starrs/The Washington Post)

“A lot of the rhetoric was aimed at the federal government, and we just didn’t know what might happen,” said Randall Eardley, a spokesman for the Bureau of Land Management, which employs about 100 permanent and 20 seasonal or temporary workers in its offices just outside Burns, Ore., the county seat.

[interstitial_link url="https://www.washingtonpost.com/news/federal-eye/wp/2016/01/05/conservation-groups-denounce-oregon-occupiers-saying-this-is-not-what-republican-teddy-roosevelt-envisioned-at-all/"]Conservation groups denounce Oregon occupiers, saying this is not what Republican Teddy Roosevelt envisioned at all[/interstitial_link]

“It became a serious safety concern for the employees,” Eardley said. He and other federal officials said self-described militia groups showed up in the Burns area in early December, weeks after a federal judge resentenced local father-and-son ranchers Dwight and Steven Hammond to five years in prison for arson.

The protesters, with harsh anti-government rhetoric and an aggressive social media campaign, began stalking some federal employees as they left work and leaving threatening messages on office phones, officials said. Some employees reported cars they did not recognize parking on the street outside their homes at night.

[interstitial_link url="https://www.washingtonpost.com/news/federal-eye/wp/2016/01/05/the-federal-bird-mecca-an-armed-group-in-oregon-is-occupying-in-land-feud/"]The Oregon refuge occupied by Bundy is one of the first wildlife sanctuaries in the U.S.[/interstitial_link]

“One of the things they seemed to be doing was trying to drum up support for their cause from the community, and that includes a lot of federal employees,” Eardley said. “People were not providing the support some of them hoped for.”

The threats were reported to federal law enforcement authorities in the area who appear content right now to monitor the situation and wait out the protesters.

Local planning for the closures, in consultation with senior officials in Washington, D.C., started weeks ago, officials said. The Bureau of Land Management made the decision to close as early as Dec. 28, concluding that the environment around Burns was not safe for its employees, who issue permits to ranchers for grazing and other uses.

The U.S. Forest Service, with about 35 employees and the Natural Resources Conservation Service and Farm Service Agency followed suit. The U.S. Postal Service stopped delivering mail to homes and business in the area last week, although the post office in Burns has stayed open.

The displaced employees are either teleworking at home, working from remote locations in other counties or on paid administrative leave if they are not set up to do either, costing the government thousands of dollars a day, officials said.

The Fish and Wildlife Service, which manages the Malheur National Wildlife Refuge 30 miles south of Burns where the armed occupiers have been since Saturday, sent its 23 employees home nine days ago, spokesman Jason Holm said.

“We love our refuge,” Holm said. “But at the end of the day, these are our buildings, and our first priority is for the safety of our employees.” He said the protesters “were contacting and talking to a lot of employees at the refuge, and making a lot of people uncomfortable.”

The Bureau of Indian Affairs, the other agency with a large federal presence in the area because it serves the Paiute Native American tribe, has stayed open because its offices are in a neighboring county.

Officials who have spoken with the employees say many of them are frustrated that they have been forced from their offices.

“It’s hard to band a bird via telework,” Holm said, describing the work of Malheur refuge employees, who track migrating birds nesting in the sanctuary.

As of Thursday night, no one could say when the federal buildings in Harney County would reopen.