Cadaver747: Firstly don't say a word. If you have an option to silently run away, do it.
If not, then just continue going forward with the same speed, calm and confident, like you own this world and every moment in your life is precious. Sometimes cheap thugs might think you are too *powerful* for them to handle leaving you alone. I strongly recommend to hang you flat keys tight in your hand like knuckles.
If it's not a case either, then prepare for some action. You have just once advantage, namely the very first shot. Possibly they'll send you a *messenger*, the weakest thug whose sole mission is to provoke you. He (or She, oh my!) will initiate a conversation in a manner "do you have a cigarette / money / dope / believe in God / etc. It doesn't really matter what you say, what matters is that you don't speak with them at all, not even a sound.
Best way is knock him with your key "knuckles" right in his face (better point to eyes or throat; less well - nose or teeth). In some cases thugs might have a second thought on pressing on and might decide to withdrew. However if the gang has a leader, even frightened, he/she will surely make an order to attack you.
Again run, or if not an option then fight as a little devil. I don't think your avatar could take out 3 or more random skilled fighters, the chances are too low. But you still have an advantage of initiative. You might fight your way to the leader and hit him/her with all you've got. If you manage to knock leader down fast enough, your chances for scare the rest of them off are quite high.
Best way is to run away. But if you still don't have a chance, you need to kick the closes person to you till you win or lose, or collapse, or even die.
Don't forget to direct your instincts along with your adrenaline flow towards one simple goal: to kill an enemy by whatever means necessary!
If you are loosing, jump on at least one of them a head-to-head punch him several times and bite his face off like it's you last meal in life...