Paranoia causes neighbors to turn on each other. A perfect example of this is how Charlie turned on Les when his car mysteriously started!
The residents of Maple St. are unable to control their fear. This leads Charlie shooting Peter Van Horn.
It seems the only person not joining the mob, was Steve. Throughout the story, he manages to keep a level head. He remains logical and rational, trying to come up with a reasonable explanation. This runs very counter to the rest of the neighborhood.