describe the people who ride on the truck that stops an the middle of the road

One day, the father awakens alert, pistol in hand. He sees people approaching, "wearing canister masks. One in a biohazard suit. Stained and filthy. Slouching along with clubs in their hands, lengths of pipe" (51). Farther down the road comes the noise of a truck. The father quickly hides their belongings and runs away with the boy. The men in the truck pass them, but the truck sputters to a stop. The men in the truck dismount in order to push it past the slope. The father sees a man from the truck standing only twenty feet away. The men in the truck look like filthy, ghostly, and disheveled. A person only described as the "bearded man" engages with the man and boy.