As I recall, cops started militarizing after one particularly violent bank robbery years ago. The bad guys had body armor and fully-automatic assault weapons. The cops had to break into a store to get some hunting rifles to give them a chance against the robbers. Some cops died before the robbers were downed, one by his own hand. Much video of the event exists. The profession was traumatized and insisted on getting at least as heavily-armed as their opponents.
Darrin Bell and Theron Heir