Cleared of armed protesters Thursday, the Malheur National Wildlife Refuge will remain closed for weeks as investigators check for explosives, gather evidence and help the Burns Paiute Tribe assess damage to their cultural artifacts.
The FBI and other law enforcement agencies will move methodically to document alleged crimes and assess damage, said Greg Bretzing, FBI special agent in charge in Oregon.
He also said the arrest of 25 occupiers in recent days shows that taking over federal property with the threat of violence "will not be tolerated in the United States. I hope that message has gotten out clearly."
The work of clearing the refuge started after the last four occupiers surrendered Thursday, giving up on a siege that started Jan. 2.
Bretzing said the first task for agents was to sweep the buildings at the refuge headquarters, 30 miles southeast of Burns, to ensure no protesters were lurking.
Most fled the compound in the days after occupation leader Robert "LaVoy" Finicum, 54, of Arizona, was shot and killed as he tried to flee police Jan. 26. The last four who gave up had been on their own from two days after Finicum was shot and other occupation leaders arrested.
At a news conference in Burns hours after the occupation ended, Bretzing described a long process to get the refuge back to normal.
And Harney County Sheriff David Ward described what he expects to also be a long process to heal divisions in the community. He urged people to abandon social media and sit down over coffee to discuss their differences.
Police face weeks of work at the refuge before 17 employees from the U.S. Fish & Wildlife Service can fully return to duty.
Authorities will have to check headquarters buildings and surrounding property for explosives, Bretzing said. An FBI affidavit to support the arrest of occupation leaders said agents developed information that the protesters deployed explosives at the refuge.
Bomb technicians from the FBI, the Portland Police Bureau and the Oregon Air National Guard and arson detectives from the Oregon State Police will take on that job, he said. It could take days, he said.
When the refuge is declared safe, evidence response teams from the FBI will take over. FBI forensic examiners will recover computers and electronic devices for evaluation, he said.