I gave this a mental run through while in Target this morning.
My plan would be to head for the back exit (follow the EXIT signs), and get people moving out that exit. Take up a covered position inside the exit area and be prepared to engage if the BG starts heading that way.
I am not sanguine about seeking out and engaging the BG. In the awful event that I take a shot at him that ends up hitting a bystander, I'd by far rather it be a case where I was shooting to defend my life rather than a case where I sought the bad guy out for battle.
I have no illusions about being robocop. I'll try to herd some of the sheep to safety, and rear guard them as they get out. Seeking the BG out is a losing proposition, IMHO. You've gone from defense to offense, and depending on where you live that might be the difference between freedom and many years in a cell with Mongo.
Just my $0.02.