Serious question. Life or death?

Okay, there were 7gang members. Well, one of my friends stabbed one because he tried to mug my friend so he stabbed the guy. well, not for sure if he's dead or what but we will stick with that he is dead. The other 6gang members ran off and witnessed everything. Okay, my friend is scarred shitless and dont know what to do. What does he do?!?! WRITE ME AS SOON AS POSSIBLE!! (and no turning in thing either)