idk what you do exactly, but when you add them as a companion (a circle portrait appear at the left bad for each companion) they fight along side you, but only melee and unarmed. increasing their strenght increase the damage output but you want to dispatch fast the ones armed you can use a knife (i find buying multiple knifes or axes - for logging- dont do nothing, you are the only one able to use them) or the gun if you progress with blair and find the bullets in the explore event (first and second playtrough i didnt find the bullets) in the police car