A man goes to a city council meeting and murders 5 people...and, yes, it was another one of those really safe, "nothing bad could ever possibly happen here" gun free zones.
One of the witnesses said, "I laid on my stomach waiting to get shot. Oh God, it was a horror."
Gun free zones = helpless victim zones...especially when the police have already been killed.
(No Looking Backwards gets the librarian nod of approval for researching the city's ordinances)