The leader of a group of armed protesters who had occupied a federal wildlife refuge in eastern Oregon for 24 days was arrested along with four others Tuesday after a traffic stop prompted gunfire that reportedly left the group's spokesperson dead and another person injured.

The FBI and Oregon State Police arrested Ammon Bundy, 40, his brother Ryan, 43, Brian Cavalier, 44, Shawna Cox, 59, and Ryan Payne, 32, at around 4:25 p.m. local time on U.S. Highway 395.

Three other people were arrested separately. The FBI said Joseph O'Shaughnessy, 45, and Peter Santilli, 50, were arrested in the nearby town of Burns, Ore. Hours later, authorities said Jon Ritzheimer, 32, turned himself in to the Peoria, Ariz., police department.

The FBI said all eight 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.

Neither the FBI nor Oregon State Police released details about what set off the gunfire at the traffic stop. The Oregonian reported that the deceased man was 55-year-old Robert "LaVoy" Finicum, the group's spokesperson. Authorities said no other information about the deceased would be released pending formal identification by the local medical examiner's office.

Finicum and Ryan Bundy allegedly disobeyed orders to surrender and resisted arrest, The Oregonian reported, citing sources. But that narrative is being challenged.

Ammon Bundy told his wife that Finicum was cooperating with police when he was shot, according to Nevada Assemblywoman Michele Fiore. A Facebook account reportedly operated by one of Finicum's 11 children, Thara Tenney, also said Finicum was cooperating.

"I want the world to know how my father was murdered today," the post said. "His hands were in the air and he was shot in the face by the American authorities. Ammon Bundy reported there are six witnesses to this evil."

One of those arrested, described only as a man, suffered non-life-threatening wounds and was treated at a hospital, law enforcement agencies said.

The protesters were heading to a public meeting in the town of John Day, about 70 miles north of Burns, to address local residents about the occupation of the Malheur National Wildlife Refuge when the traffic stop took place, law enforcement officials told Fox News.

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.

The Harney County Hospital in Burns was placed on lockdown out of concern that the protesters may cause a disturbance there. 

Ammon Bundy's group, calling itself the Citizens for Constitutional Freedom, seized the refuge's headquarters on Jan. 2 in protest of what they viewed as onerous federal land restrictions, as well as the prison sentences of two local ranchers convicted of setting fires. 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.

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

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.

"I am pleased that the FBI has listened to the concerns of the local community and responded to the illegal activity occurring in Harney County by outside extremists," Sen. Jeff Merkley, D-Ore., said in a written statement. "The leaders of this group are now in custody and I hope that the remaining individuals occupying the Malheur National Wildlife Refuge will peacefully surrender so this community can begin to heal the deep wounds that this illegal activity has created over the last month."

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.

Fox News' Chad Pergram and The Associated Press contributed to this report.