The FBI on Tuesday arrested the leaders of an armed group that had occupied a national wildlife refuge in Oregon for the past three weeks, conducting a traffic stop that prompted gunfire -- and one death -- along a highway through the frozen high country.

Militant leader Ammon Bundy and his followers reportedly were heading to a community meeting at the senior center in John Day, a Grant County town about 70 miles north of Burns, to address residents to discuss their views on federal management of public lands.

The Oregonian newspaper reported several hundred people had gathered Tuesday evening at the John Day Senior Center and were told the "guest speakers" would not be appearing.

In a statement, the FBI and Oregon State Police said agents had made six arrests: Bundy, 40; his brother Ryan Bundy, 43; Brian Cavalier, 44; Shawna Cox, 59; and Ryan Payne, 32, during a traffic stop Tuesday afternoon on U.S. 395. Authorities said another person, Joseph Donald O'Shaughnessy, 45, was arrested in Burns.

One of those arrested suffered wounds that were not life-threatening after shots were fired and was treated at a hospital, the agencies said. Another person "who was a subject of a federal probable-cause arrest is deceased," they said. The agencies said they would not release further information about the death, pending identification by the medical examiner.

Ammon Bundy

Ammon Bundy's group, which has included people from as far away as Arizona and Michigan, seized the headquarters of the Malheur National Wildlife Refuge on Jan. 2 as part of a dispute over public lands in the West. It was unclear how many people remained in the buildings Tuesday night.

The confrontation came amid increasing calls for law enforcement to take action against Bundy for the illegal occupation of the wildlife refuge.

Many residents of Harney County, where the refuge is, have been among those demanding Bundy leave. Many sympathize with his criticism of federal land-management policies but opposed the refuge takeover. They feared violence could erupt.

Ammon Bundy recently had begun traveling into Grant County to try to drum up sympathy for his cause.

The Bundys are the sons of Nevada rancher Cliven Bundy, who was involved in a high-profile 2014 standoff with the government over grazing rights.

The FBI said the people arrested face a federal felony charge of conspiracy to impede officers of the United States from discharging their official duties through the use of force, intimidation or threats.

No indictments or federal charging documents had been made public.

Federal law enforcement officers converged on the wildlife refuge after the arrests and were expected to remain at the site throughout the night. It was unclear how many members of the armed group, if any, were at the refuge when the law enforcement officers arrived.

The militants, calling themselves Citizens for Constitutional Freedom, came to the frozen high desert of eastern Oregon to decry what it calls onerous federal land restrictions and to object to the prison sentences of two local ranchers convicted of setting fires.

Specifically, the group wanted federal lands turned over to local authorities. The U.S. government controls about half of all land in the West.