Well, the consensus seems to be unanimous. There is a bit of differing opinions between warning yells, warning shots, and just shooting.
Thank you all for the info.
However, another wrinkle. Many CCW holders choose to carry revolvers. While the relative merits of this style versus a semiautomatic have been debated many times, what would be the appropriate action for someone with 5 or 6 rounds (plus speedloaders, but those take some time, yes?) ready? Would it be Woo-style, with revolver in one hand, and the BUG (another revolver? A small semiauto?) in the other? Would you shoot each BG once, or just shoot one or two of them until they drop?