Armed protesters, including three sons of a Nevada rancher who battled with the government in 2014, vowed to occupy a federal building in Oregon for “as long as it takes,” as state and federal officials on Sunday sought to defuse the situation.

The protesters took over a federal wildlife refuge in a remote area near Burns, some 280 miles east of Portland, to protest the prosecution of a father and son facing jail time on an arson charge for burning 130 acres of land. Prosecutors said the fire was set to hide poaching, but the ranchers, who face five years in prison, and the protesters supporting them say it was set to stop invasive plants.

"We will be here as long as it takes," said Ammon Bundy, a spokesman for the group and the son of Cliven Bundy, a Nevada rancher who clashed with the feds two years ago.

"We have no intentions of using force upon anyone, (but) if force is used against us, we would defend ourselves," Ammon Bundy said while issuing a broad appeal for others to come join the occupation in a show of support.

Those occupying the refuge claimed they had as many as 100 supporters with them. The occupation came shortly after 300 marchers paraded through Burns in support of ranchers Dwight Hammond Jr. and Steven Hammond, who report to prison Monday.

The tense situation involved the Oregon State Police, the Harney County Sheriff’s Office and the FBI.

Harney County Sheriff Dave Ward told people to stay away from the building as authorities work to defuse the situation, the Oregonian reported.