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Gun-toting protesters remained holed up in a federal wildlife refuge in Oregon on Monday night even though the two men whose prison sentences sparked their action turned themselves in to authorities and repudiated the protest.

The protesters said they wouldn't budge until the government addresses their demands, but the FBI said it was hoping to bring a "peaceful" end to the standoff at the remote Malheur National Wildlife Refuge.

"We feel we have exhausted all prudent measures and have been ignored," said Ammon Bundy, co-leader of the self-styled Citizens for Constitutional Freedom, who said the group wants the federal government to "remove its unlawful presence in this county."

Bundy's group seized the government property after splintering off from a larger protest about ranchers' rights in the small town of Burns.

The initial protest in Burns was in support of Dwight Hammond, 73, and his son Steven, 46, who faced more jail time for setting fires that spread to government land after their initial sentences were extended by about four years each.

The Hammonds surrendered Monday at the federal prison in San Pedro, California. Their lawyers said they plan to appeal to President Barack Obama for executive clemency.

The ranchers distanced themselves from the protesters, and their lawyer told police that "neither Ammon Bundy nor anyone within his group/organization speak for the Hammond family."

Harney County Sheriff David Ward directly addressed those at the refuge during a news conference Monday, telling them: "It's time for you to leave our community, go home to your families and leave this community peacefully."

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"You said you were here to help the citizens of Harney County," Ward said. "That help ended when that protest became an armed occupation."

Ward said in a separate video message Monday that that he was "very proud of the citizens of Harney County in the way that they've stood up to this."

No government employees were at the site at the time because of the holidays. It wasn't clear how many people had occupied the building, but those inside have asked for others to join them in several videos posted online.

Related: Meet Ammon and Ryan Bundy, the Activists Leading the Oregon Standoff

The ringleaders are Ammon and Ryan Bundy — sons of Cliven Bundy, the Nevada rancher known for another standoff with the federal government in 2014.

The FBI said in a statement Sunday that it was working with local and state police "to bring a peaceful resolution to the situation."

The agency said it wouldn't be providing details of its response because of "safety considerations for both those inside the refuge as well as the law enforcement officers involved."

Several pickup trucks continued to block the entrance to the refuge Monday, with armed men wearing camouflage and winter gear stationed outside.

Although there was no visible sign of police, authorities have warned people to stay away and the county has canceled school until next week as a precaution.

"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," the Harney County Sheriff’s Office said in a statement Sunday. "We ask that people stay away from the refuge for their safety."

Related: Oregon Standoff: Armed Protesters, Political Reaction and #YallQaeda

The Bundy brothers and their followers unveiled a redress of grievances addressed to several local officials and alleged that the federal government targeted the Hammonds because they refused to sell their land "to a federal agency."

Bundy insisted that he and others had reached out to local officials about the case before taking over the refuge but never got a response. He said the purpose of the gathering is "to go to work ... to unwind the unconstitutional land transactions that have taken place here."

"We have very specific plans that are going to take place," said Bundy, who gave no specifics.

Ammon Bundy told NBC's TODAY on Monday that the occupiers have no intention of committing violence unless the government intervenes.

"The only violence that, if it comes our way, will be because government is wanting their building back,'' he said. "We're putting nobody in harm's way. We are not threatening anybody. We're 30 miles out of the closest town."

The Bundys claim they were asked to intervene by an unidentified "county representative" who alleged that "he and other county representatives are being intimidated by the FBI." He didn't provide further details of this allegation.