The wildlife agency said no federal wildlife employees were in danger in the occupation. “While the situation is ongoing, the main concern is employee safety and we can confirm that no federal staff were in the building at the time of the initial incident,” a Fish and Wildlife Service press officer said.

The group appeared to be led by Ammon Bundy, a rancher whose family became a symbol of antigovernment sentiment in 2014, when his father inspired a standoff between local militias and federal officials seeking to confiscate cattle grazing illegally on federal land. In a statement captured on video, Mr. Bundy said that his group was “prepared to be out here for as long as need be” and would leave only when the people of Harney County “can use these lands as free men.”

“We’re out here because the people have been abused long enough really,” he continued. “Their lands and their resources have been taken from them to the point where it’s putting them literally in poverty, and this facility has been a tool in doing that. It is the people’s facility, owned by the people.”

Afterward, a group broke off and occupied the refuge headquarters.