The FBI and Oregon State Police on Tuesday arrested the leaders of an armed group that has occupied a national wildlife refuge 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 were reportedly heading to a community meeting at the senior center in John Day, a Grant County town about 70 miles north of Burns, to address local residents to discuss their views on federal management of public lands.

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

In a statement, the FBI and Oregon State Police said agents had made seven arrests: Bundy, 40; his brother Ryan Bundy, 43; Brian Cavalier, 44; Shawna Cox, 59; and Ryan Payne, 32, during a traffic stop on U.S. Highway 395 Tuesday afternoon. Authorities said two others — Joseph Donald O’Shaughnessy, 45, and Peter Santilli, 50 — were arrested separately in Burns.

Oregon State Police confirmed that its troopers were involved in the traffic-stop shooting, though neither agency released details about what started it. One of those arrested, described only as a man, suffered non-life-threatening wounds and was treated at a hospital, the agencies said. Another man “who was a subject of a federal probable cause arrest” was killed, they said. The agencies said they would not release further information about the death pending identification by the medical examiner.

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 long-running dispute over public lands in the West. 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 people, if any, remained in the buildings.

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 located, have been among those demanding that Bundy leave. Many sympathize with his criticism of federal land management policies of public lands but opposed the refuge takeover. They feared violence could erupt.

Ammon Bundy recently had begun traveling into Grant County to try to drum up more 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 Tuesday 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.

The state police said it would investigate the officer-involved shooting, with help from the Deschutes County Major Incident Team and the Harney County District Attorney’s Office.

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.

Associated Press reporters Lisa Baumann in Seattle; Keith Ridler in Boise, Idaho; and Terrence Petty in Portland, Oregon, contributed to this report.