If one does find themselves in the situation like that, and they can't escape........I recommend doing what I did....feign momentary submission and THEN.....hit the Leader/Mouth of the group FIRST as HARD AS YOU CAN, for MAXIMUM DAMAGE, and fight like hell!
That's the key. The leader if you can, otherwise the nearest threat... should go down as hard and as violently as you can possibly put him down. He should be howling in pain with his knee inside out and coughing and choking on his own blood. Something that will get the attention of the rest.
To quote Wyatt Earp (in Tombstone);
Wyatt Earp to Ike Clanton: "You die first, get it? Your friends might get me in a rush, but not before I make your head into a canoe, you understand me?"
Every man there should feel as though the first/next one near you will get torn in half before the rest overtake you.
Much of this can be done psychologically. If you have real intent, they will see it in your eyes and your body language. What you say and how you say it will further drive it home.
I can remember situations as early as high school and as recent as some of the security work I have done. You can look in a mans eyes and if you have real intent, your eyes will tell him that you will kill him, his eyes will tell you if you have him cowed, or if a confrontation is inevitable.