Marijuana growers.
"For the last three summers, large marijuana operations have been discovered in the Chequamegon-Nicolet National Forest in northern Wisconsin. In each of those busts, law enforcement made numerous arrests, almost all natives of Mexico here illegally. Confiscated weapons included handguns, AK-47s and a .308-caliber rifle with ammunition magazines taped together." Forest Service to WI Hunters: Beware of Armed Marijuana Growers
In Colorado the growers rent an empty warehouse.