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.