Trying to prepare for this is like trying to prepare for a suicide bomber with C4 strapped to his chest
All fights, including physical ones cannot be prepared for, except to train and increase your speed, vision, and skills. The shooter probably is not prepared either for a good shooter putting 230 grn. hardballs through his gas mask, and/groin, even if he had a plate in his groin area, a .45 will ruin his day!
You have to do something ... sitting there and watching your family die is not an option!!! I would attack without a gun in that situation, I assure you.