— -- Two eastern Oregon ranchers convicted of arson on federal land turned themselves in to a California prison this afternoon, as militia members -- who say the ranchers are going to jail for a crime they did not commit -- continue an armed occupation of a wildlife refuge in the state that's on federal property.
Dwight Hammond Jr., 74, and his son, Steven Hammond, 46, were convicted three years ago of setting fires in 2001 and 2006 on lands managed by the U.S. Bureau of Land Management, "on which the Hammonds had grazing rights leased to them for their cattle operation," according to the U.S. Attorney’s Office.
After a years-long legal battle, the Hammonds turned themselves in today at Terminal Island in San Pedro, California, at about 5 p.m. ET.
Arson on federal land carries a five-year mandatory minimum sentence, but the Hammonds argued that the rule was unconstitutional.
While a trial court "imposed sentences well below what the law required based upon the jury’s verdicts," according to the U.S. Attorney's Office, the Ninth Circuit Court of Appeals upheld the federal law, calling the sentence "not grossly disproportionate to the offense."
The Hammonds' five-year prison terms were imposed in October 2015, with credit for time they already served.
After a rally for the Hammonds on Saturday, armed militia, including sons of Cliven Bundy -- who was involved in a standoff with the government over grazing rights in Nevada in 2014 -- initiated the occupation of the headquarters of the Malheur National Wildlife Refuge.
Ammon Bundy, one of those sons, called the earlier rally successful, but said Sunday of the Wildlife Refuge standoff, "If we do not make a hard stand, we will be in a position where we won't be able to as a people."
Harney County Sheriff's David Ward's message to the occupiers today: "It's time for you to leave our community."
He asked them to end the occupation peacefully now that the Hammonds have turned themselves in.
Ward said what began as a peaceful protest took "an unfortunate turn when some of those folks broke off and began an armed occupation."
Bundy said today the occupying group is called "Citizens for Constitutional Freedom" and its purpose is to "restore and defend the Constitution."
He said he came to the Burns, Oregon, area about eight weeks ago and met with the Hammonds "many, many times."
"I watched them in tears multiple times," he said.
Bundy today called the Hammonds a "good ranching family" and said they are going to prison for a crime they did not commit.
Attorneys for the Hammonds told ABC News in a statement earlier today, that, "as the Hammonds have previously stated, they will be reporting to the United States Bureau of Prisons today to serve their sentences."
"Dwight and Steven Hammond respect the rule of law," the statement continues. "They have litigated this matter within the federal courts for over five years and, in every instance, have followed the order of the court without incident or violation. That includes serving the entire sentences imposed in this case by the judge who heard the evidence at trial and who concluded that imposition of a five-year sentence under these circumstances would 'shock the conscience.'"
"The Hammonds will continue their legal efforts to renew their grazing permits," the attorneys say. "They will also pursue Executive Clemency. We hope that President Obama will agree with us and with the veteran judge who presided over the trial that the mandatory five-year minimum sentence is far too long for these ranchers."
Karyn Gallen, the niece of Dwight Hammond and cousin of Steven Hammond, said today that the occupation "is in no way connected to the Hammond family."
"The Hammonds have always been about family first," Gallen said. "I think it's important for Harney County ... to show support, but it has always been the request of the family to keep that peaceful."
Bundy told ABC News earlier today that, while he does not speak for the Hammonds, "We have spoken many, many times, and we understand each other on this issue."
"The Hammonds are only going to jail because they just feel there's nothing else for them to do," Bundy said. "But they very well know that this is wrong, along with all their neighbors and the other ranchers in the area."
White House Press Secretary Josh Earnest said President Obama is aware of the refuge standoff, but said it is a “local law enforcement matter” despite the fact that it involves federal land.
“This ultimately is a local law enforcement matter. The FBI is monitoring the situation and offering support to the local law enforcement officials as they try to deal with that,” Earnest said in today’s White House briefing.
“We’re hopeful that that situation can be resolved peacefully without any violence,” he said.