You could always call a time out...
If they watch enough TV or play enough video games, they might go for it.
Anyway, why after expending all your ammo have you not neutralized the threat?
Were you totally outnumbered before the SHTF?
Did you have no way to run away before the first shot? Was your panic so uncontrollable, or your shooting just so poor from adrenaline or a thousand other things that you just couldn't hit the BG?
or couldn't hit them all?
or was your sin the worst of all - failure to bring enough ammo?
I assume they've been returning fire and you aren't immobilized yet, so they aren't shooting any better then you are. Guess i'd want to use available cover and run like the wind, only a wind that darts from cover to cover, zigs and zags.