If you get close enough (just slightly further than the Quick Kill/Grab point) an enemy will sometimes (especially in the earlier levels) back off, wave his hands as if to say "don't shoot" then say similar to "It-- it's you!!!!"; giving you time to shoot him. Also, sometimes by performing a quick kill near another enemy, sometimes they will put a hand over their mouth as though they are about to vomit, and say something similar to "I think I'm gonna be sick!" or "Oh my God!" followed by a vomiting sound. This also gives you some extra time to shoot the enemy. Note: This does not work on all Yakuza gang members.