An FBI operation to arrest leaders of a militia has ended with one man dead and another wounded on a highway in the US state of Oregon. Seven people from the armed group are now in custody.
Ammon Bundy, 40, the leader of the militia that has occupied a national wildlife refuge on federal land for the past three weeks, was among the people arrested after Tuesday's shooting.
The FBI said in a statement that one individual "who was a subject of a federal probable cause arrest is deceased".
Bundy's militia, which has included people from as far away as Arizona and Michigan, seized the headquarters of the Malheur National Wildlife Refuge on January 2 as part of a long-running dispute over public lands in the western United States.
Al Jazeera's Gabriel Elizondo reported that the man killed was LaVoy Finicum, the group's second-in-command.
He said the shooting happened on a highway not far from the refuge near the city of Burns. "It appears the FBI and local police initiated an operation to stop the militiamen," he said.
Several members of the militia were arrested at the scene of the shooting and others elsewhere.
An unknown number of members - along with women and children - were believed to still be holed up at the refuge, and militiamen put out calls on social media asking for back-up.
Armoured FBI convoys were reportedly heading from the airport in the direction of the building.
"This could indicate that by daybreak, law enforcement will have a presence at the refuge, possibly surrounding it or cutting off access roads, which would be a clear further escalation," Elizondo reported.
JJ MacNab, a Washington-based writer on anti-government movements, said several well-known anti-government figures had reportedly been heading to the refuge before the arrests on Tuesday.
"I think that a lot of people were on the way to join the group. Some of names recently shown up ... are a little bit scary. They idolise people like Timothy McVeigh," MacNab told Al Jazeera.
She said that her concern now was for the children still possibly inside and a further escalation of violence.
After the shooting, authorities arrested several other people connected to the militia.
John Ritzheimer, a prominent member, was arrested for conspiracy at his home in Arizona. He had been in Oregon as part of the occupation, but recently returned home. Ritzheimer gained national attention when he held anti-Muslim protests outside a mosque in Phoenix last year.
Speaking to Al Jazeera's AJ+ in January, the dead man Finicum said that he joined the occupation to defend freedom, rejecting claims the standoff was racially motivated.
"My heart goes out to anyone who has violence perpretated on them ... we welcome any support from any community, freedom has no colour," Finicum, a farmer, said.
Ammon Bundy is the son of Nevada rancher Cliven Bundy, who was involved in a high-profile 2014 standoff with the government over grazing rights.
"LaVoy Finicum was shot and murdered in cold blood today in Burns Oregon … He had his hands up and was shot three times," Cliven Bundy said in a Facebook post.
Al Jazeera's Anealla Safdar contributed to this report
| Oregon siege: What the armed group wants and why
Source: Al Jazeera