Pellet Gun Halts Mail Service

How does what sounds like a few kids cause mail deliver to be halted for three weeks for portions of three streets in Evanston? I know that pellet guns are not in the famous phrase:

Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds.

, but come on. Get a police escort while delivery in going on. Just park the officer on the street. I would think that would suffice.