Ammon Bundy, the leader of an armed militia which has occupied a wildlife refuge in Oregon, has been arrested, police say.
One person has been killed in the shootout.
Ammon Bundy and four others were arrested during a traffic stop. One person was injured. Three others were held in separate incidents.
The militia occupied the refuge on January 2 to support two ranchers jailed for setting fire to federal land.
They say the government has taken land illegally from ranchers for decades.
Other members of the group were reportedly still at the Malheur National Wildlife Refuge in eastern Oregon, where the FBI was setting up a perimeter.
FBI officials said in a statement that Ammon Bundy, 40, was arrested in a traffic stop on Highway 395 along with his brother Ryan Bundy, 43, Bryan Cavalier, 44, Shawna Cox, 59, and Ryan Walen Payne, 32.
Two other activists connected to the group, Joseph Donald O’Shaughnessy, 45, and Peter Santilli, 50, were later arrested, separately, in Burns, Oregon.
According to The Oregonian newspaper, Ammon Bundy was en route to a community meeting in John Day, Oregon, where he was scheduled to be a guest speaker, when authorities stopped his vehicle.
According to the newspaper, Ryan Bundy was injured in the arrest, suffering a minor gunshot wound. Authorities did not release the identity of the person killed.
However, local media named the man as Arizona native Robert “LaVoy” Finicum, a regular spokesman for the group.
His daughter, Arianna Finicum Brown, told The Oregonian he was a “good, good man, through and through”.
Some 25 miles of Highway 395 was shut in both directions following the incident, local officials said.
Another occupier of the refuge, Jon Eric Ritzheimer, 32, surrendered to police in Arizona on January 26.
In October 2015, a federal judge ruled the sentences on two Oregon ranchers, Dwight and Steven Hammond, for burning federal land were too short and jailed them for about four years each.
Angered by the ruling, Nevada native Ammon Bundy began a social media campaign backing them and travelled to Burns, Oregon, organizing meetings.
Ammon Bundy’s group attracted supporters from across a number of states and he called it Citizens for Constitutional Freedom. On January 2, the armed militiamen took over the Malheur National Wildlife Refuge – and widened the range of demands.
It is an extension of the Sagebrush Revolution of the 1970s and 1980s that demanded the transfer of federal land in many western states to local control.
Ammon Bundy’s own father – a Nevada rancher – had been involved in a protest over cattle-grazing rights in 2014. One policy is to try to persuade ranchers to tear up their federal grazing contracts.
Although many local residents are sympathetic with its cause, many also oppose the occupation of the refuge. Even the local ranchers who are serving the longer sentences distanced themselves from the militia.
The militia term has a complex history and generally refers to those outside the official military who can be called on in times of need. The US Constitution refers to the president having command of “militia of several states” and that Congress “can call forth militia” to tackle insurrection and invasion.
Those who form such militias cite the constitution and various references in federal and state law as granting them legality.