I pulled this from Mark Boslough's FB page, who grabbed it from the FB page of Moms Demand Action for Gun Sense in America. It was apparently taken at a Home Depot in Tarrant County (Ft. Worth area), Texas.
I guess these vigilant militia members are looking for bad guys.
A question: how do we know that they're not the bad guys?
Then there is the 'defaced' version from Mark's FB page: