As I understood, the combat went this way up till now.
Initiative order: Trog, Concrete, Vest1, Vest2, rest of the gangers.
IP1: Trog misses; Concrete takes out a ganger; two gangers attack Trog, a third goes after Concrete, and the one standing back draws a revolver
IP2: Trog takes out a ganger; Concrete takes out a ganger; Trog's second opponent backpedals and the final ganger takes a shot.
IP3: Trog charges the ganger with the revolver.
Turn 1 is complete. Please correct me if you see it differently.
BTW we don't have to roll initiative each pass, but each combat turn.
Also i think that Trog has several levels of critical strike (cannot confirm as i don't find Trog posted) which are directly added to the DV of unarmed attacks.