Benelli 3" 12 ga. first shots sabot slugs that you have a chance at the 100-50 yard range to put through the chest or head. Keep shooting and loading with 00 buck at the head and neck til there's nothing left to shoot.
The only other firearm I'd choose is .300 WM Tikka with Premium Fail Safe or Nosler cartridges. Better be sure to make every round count!
Lord, I wouldn't hope that situation on anyone though. Whew!
Well, maybe there are a few lowlifes you see in the news...