When Gang of Devils dies, it deals 3 damage divided as you choose among one, two, or three target creatures and/or players.
"Well, how could I know they'd explode?" —Gregel, township militia
Official Rulings for Gang of Devils
5/1/2012 : You divide the damage as you put Gang of Devils's triggered ability on the stack, not as it resolves. Each target must be assigned at least 1 damage. (In other words, as you put the ability on the stack, you choose whether to have it deal 3 damage to a single target, 2 damage to one target and 1 damage to another target, or 1 damage to each of three targets.)