In light of recent tragic and morbidly shocking mass shootings from Connecticut, to Washington and Colorado; one may begin to wonder and question; “for such dire situations what do modern police have access to or "carry" in their vehicles to possibly mitigate such egregious events? And how do police keep such arms safe until needed?”
Fundamentally, American law enforcement professionals always carry at least a "service pistol" referring to either a revolver (typically holding 6 rounds of ammunition) or an "semi-automatic" pistol (referring to its action – that it fires once each time the trigger is pulled and reloads itself until empty). Automatics may hold as many as 15 rounds based on the make and model. Such firearms have been the staple of law enforcement since its inception. Handguns, however, have no actual way to be secured from snatching or being wrestled away from an officer. Modern holsters are designed to act as partial “safes” requiring a direct and deliberate upright pull that could, theoretically, only be performed by the officer. In reality, the force of a struggle can sway the officers' belt to and fro so that such safety measures can be jeopardized.
The workhorse second to handguns in the law enforcement arsenal is the shotgun. Typical issue is a 12 gauge model often pump-action (requiring physical motion of the action to chamber a round after each fire) but progressing to a semi-automatic shotgun. Simplistically put, once the officer fires a shell, the shotgun reloads itself using the recoil of the fired shot similar to the semi-automatic pistol. This can give 8 to 10 shots without the need to reload. Shotguns prove quite effective in several applications where close-range situations exist.
The third element in an officers' arsenal is the centerfire rifle. Admittedly this is akin, if not the same, as a hunting round; long range capabilities, relatively powerful, and holding multiple rounds (in a magazine or "clip" typically holding 20-30 rounds). The purpose behind such a rifle would be to engage with assailants at a long distance or perhaps through obstacles (e.g. wood siding, vehicle doors, etc.). Common centerfire rifles for police include the Ruger "Mini-14" and the AR-15 that both fire the 5.56mm round also the standard for U.S. armed forces.
Both of these "long guns" are stored in locking contraptions within the police vehicle either in the front seat area or in the trunk requiring a key for access. In this sense, the police cruiser has become a miniature arsenal.
For the civilian business and/or homeowner there are numerous options for gun safes ranging from electronic fingerprint-recognition handgun safes that occupy a nightstand to full-size traditional safes weighing over a thousand pounds and holding 40 or more firearms.
The well-equipped modern police department often has a “military-style” armory within the station that may include a firing range. Although such facilities may seem extreme - the realities of hostage situations and mall shootings may warrant such a range of firearm options.