This section of the novel comes at the beginning, as we see Montag and his colleagues go off to a house, following a tip from a neighbour, and burst in to find a secret stash of books and magazines. However, what is crucially different with this episode is that the police have not already been round and taken away the person responsiible. Montag explains that normally when they arrive, the house is empty and all they have to do is burn it down. This time, however, they have to contend with the old lady herself and her reactions at having such an unwelcome intrusion. Note what Montag says:
How inconvenient! Always before it had been like snuffing a candle. The police went in first and adhesive-taped the victim's mouth and bandaged him off into their glittering cars, so when you arrived you found an empty house. You weren't hurting anyone, you were hurting only things!
Thus it is inconvenient for Montag to face a human response to his job, and to cope with his guilt and sadness at what he does by having to do it in front of another human being, like himself.