A persons "natural" reaction to this is to put their hands in front of their face to sheild their eyes from the blinding light. This would possibly reveal whether or not they were armed. If they are...shoot, if not, try non lethal forms of stoppage, possibly OC spray or non-lethal loads designed for the 12ga.
I have pondered this type of ? many times, the problem for me is that there is no commercially available non-lethal load for my M-4.[:@][]