Pages 120-130
After Guy burnt captain Beatty, beat the snot out of the other two firemen with them, he gets attacked by the mechanical hound and gets most of the injected in the leg. He then tried to run away down the alley, crying and pleading with his leg to move. He runs away towards Faber's house but realizes he can't go there in fear that he will be in danger too. So he keeps walking then a car full of teens almost run him over.
The importance is that Montag is finally leaving his old life to be free from the rules of being a firemen.