Law enforcement officers block a road near the headquarters of the Malheur National Wildlife Refuge outside Burns, Oregon

Law enforcement officers block a road near the headquarters of the Malheur National Wildlife Refuge outside Burns, Oregon January 28, 2016. U.S. authorities tightened security after their standoff with the occupiers turned violent on Tuesday when officers stopped a car and arrested occupation leader Ammon Bundy and his group near the Malheur National Wildlife Refuge. REUTERS/Jim Urquhart