A wildlife sanctuary in rural Oregon is closed indefinitely after protesters took control of the facility.

A posting on the U.S. Fish & Wildlife Service’s website says “an unknown number of armed individuals have broken into and occupied” the Malheur National Wildlife Refuge, which is located approximately 30 miles southeast of Burns, Oregon, in the state’s southeast quadrant.

The service says there weren’t any employees in the refuge when it was overtaken.

According to The Oregonian, the group of about 20 military began occupying the refuge some on Saturday to protest how the government handled criminal proceedings against two ranchers.

In October, Dwight Lincoln Hammond and his son, Steven Dwight Hammond, received five-year prison sentences for allegedly setting fires on lands the Bureau of Land Management had leased to them for cattle grazing, the Department of Justice said in news release at the time. The Hammonds originally got a more lenient sentence after arguing the mandatory minimum of five years was unconstitutional, but an appeals court ultimately ruled the five-year term fit the crime, threw out their original punishments and resentenced them to the mandatory minimum.

The Hammonds were due to report to prison on Monday, according to The Oregonian, but that hasn’t stopped the militants from staging their protest.

CNN reported the group’s leader, Ammon Bundy, told the network they will not leave the land until the government meets their demands, and has threatened to use force in a self-defense capacity if authorities used force against them.

If the name sounds familiar, it could be because anti-government protests run in the family.

Bundy is the son of Cliven Bundy, who staged a widely publicized armed standoff with the federal government over land rights issues in Nevada in 2014. According to The Oregonian, attorneys for the Hammonds have said that Ammon Bundy does represent their clients.