Actually, no. It was an off duty DC cop.
Citizens in DC, according to the "public servants" who rule over the district, are too stupid and/or incompetent to determine that this scumbag was robbing a gas station under force, or threat thereof, so they would have never been able to intervene.
But DC cops are trained from birth to instantly determine a robbers proclivities, and are graciously given the rare privilege of carrying a death machine assault pistol to thwart the bad guys attempts to deprive a citizen of his or her property and life.
It's a good thing that the gas station owner did not posses one of these death machines or somebody may have gotten hurt.
Update: The bad guy died. So Sorry.
He didn't try to rob the gas station attendant; he instead tried to rob the off duty cop and got a chest full of holes for his trouble. Fortunately the victim was an "Only One" and was carrying his "service revolver," because if it had been one of DC's unarmed, unwashed proletariat the story would likely have been tragic.