Darn, depends on a lot of things. What kind of gun I was armed with, what those guys were armed with, how much ammo I had, how much elbow room I have in back of me, and why they are after my butt.
My initial thought is to figure out who the leader is and take him out first. That just might take the wind out of the sails of the other guys. 10 to 20 yards gives me a little bit of breathing room to be backing up while firing. I think I would rather have one DOWN AND OUT definitely out of the fight rather than three wounded MAYBEs out of the fight.
But heck, if they are firing at me the whole time, and there is no cover around, then unless they are all very bad shooters, or I am extremely lucky, the situation will probably turn out very bad for me. They will be close enough that it is unlikely all of their shots would miss me. Ain't like in the movies....