Definition
An active shooter is defined by the U.S. Department of Homeland Security as "an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearm[s] and there is no pattern or method to their selection of victims." Note that this definition is a simplification it that many "active shooters" use mixed methods, such as firearms and explosives, arson, hand-to-hand weapons, vehicles, etc., as part of the attack. An attacker may become an active shooter as part of a 'double-tap' attack where they initiate a first incident to trigger an emergency response and then attack emergency responders. Auxiliary members should always be aware of this possibility and the potential need to protect other (unarmed) responders until law enforcement can mobilize.
In 64 [of 160] incidents where the duration of the incident could be ascertained, 44 (69.0%) of 64 incidents ended in 5 minutes or less, with 23 ending in 2 minutes or less. Even when law enforcement was present or able to respond within minutes, civilians often had to make life and death decisions, and, therefore, should be engaged in training and discussions on decisions they may face. --- "A Study of Active Shooter Incidents in the United States Between 2000 and 2013". US Department of Justice, Federal Bureau of Investigation. 24 September 2014
In order to deal with the potential complexity and the ambiguity of 'shooter' (who may be you shooting back), we will use the term 'aggressor' in the remainder of this document wherever possible.
Priorities for response will depend on where you are in relation to the violence:
Priorities For Response
As we are not law enforcement, the typical volunteer does not have the authority or training to 'go in after' the aggressor (volunteers who are retired law enforcement or qualify in advanced tactical training may be excepted). Our potential roles in a protracted incident would focus on perimeter control, communications support, chaplaincy, assistance in parent-child-reunification, and medical force protection. One of the missions of the Auxiliary, however, is to disperse trained responders in the community ahead of a no-notice incident to maximize the chance of someone being nearby when needed. Understanding that these incidents are unusual, it is possible that one or more volunteers may be present, on or off-duty, when one occurs.
Hot Zone
If you are at ground zero (e.g. in the same room as the shooter) when an incident occurs, then this simply devolves to a defense of person circumstance and should be treated no differently: act as necessary to protect life (yours and that of other bystanders). Afterwards, communicate with Dispatch and begin response operations (e.g. assist wounded) until someone arrives to take over and formally assign you. If the scene is safe, clear and holster your weapon as soon as possible. Always be certain that Dispatch knows that armed friendlies are present, how many you are, whether you are in or out of uniform, etc. In many cases, someone will have called 9-1-1. If convenient, simply find out who it is, have them tell Dispatch that you are present, and maintain focus on the critical tasks of triage and initial response, using the bystander with the phone to relieve you of communication overhead. Do not disturb the scene prior to arrival of law enforcement any more than is necessary to protect life.
Warm Zone
In the event of an active shooter or similar threat nearby but not in your same location (e.g. in the same building), your responsibility is to:
As soon as you hear gun shots, you should be moving. Put cover between you and the danger. Put yourself (and your weapon) between the danger and other bystanders. If it is possible to escape and help bystanders escape, do so. If not, close doors, barricade doorways, or whatever is necessary to secure your position. Identify yourself. Be wary of drawing your weapon until it is necessary so that you are not mistaken for the aggressor. Use force if necessary to protect your life and that of those around you but do not go seeking trouble. Remember in particular, that many aggressors use long-arms and soft body armor: going against the aggressor with a concealed-carry handgun, limited ammunition, no armor, and no support may simply make you a victim. It is often better to find and defend a strong position, protecting those you can.
As soon as your position is as secure as you can make it, communicate with dispatch (or, again, locate someone who has already called 9-1-1 so that you can focus on life protection). Make certain that dispatch knows that armed friendlies are present. If you have your radio, follow Missouri protocol by setting your primary channel to Law Mutual Aid to coordinate with law enforcement and your secondary to Multi-Disciplinary Mutual Aid (MTAC) to communicate with the larger response, such as medical. If you know and have programmed the channel for local law (e.g. municipal PD), announce yourself there first, say that you are switching to Law Mutual Aid and then do so. Be aware that it is becoming common for law enforcement to deploy singly or in pairs as soon as they arrive on scene. Also keep in mind that a sophisticated aggressor may be listening to radio traffic. Keep dispatch aware of important information: where the aggressor is, how many, what they are armed with, how many victims and where they are located, etc., but do not monopolize the channel. By securing your area and coordinating with dispatch, you provide a possible safe initial entry point ("beachhead") for arriving law enforcement. As you secure a means of retreat, you should then create a rally point out of the Warm Zone in the Cold Zone so that victims can be gotten out and other responders in (see Cold Zone, below.)
If you have wounded nearby, and if your situation is secure (if, for example, you have a partner to watch your back), begin tending to wounded. Otherwise, direct bystanders if possible ("You in the blue shirt, take this and put direct pressure on that wound. Is anyone here trained in First Aid?"). Where it is possible to give bystanders something useful to do, it may keep them (and you) calm and focused. As taught in CERT Training and First Aid we do not move wounded unless it is necessary to save their lives, but if it is necessary, say if someone is going through and shooting wounded, by all means move them, or, better, have someone else move them while you watch their back.
Once law enforcement arrives on the scene, one of two things may occur. If you have coordinated with the specific LEOs before, are wearing uniform, vest or jackets (or are otherwise readily identifiable), and are in close communication with them, then ideally, they can simply move in past you or check your location, verify your identity, and continue with their sweep. If you are not in close communication and they are not directly familiar with you, you will need to place your weapon in a non-threatening posture before they make entry. If you have entering LEOs on one side and an armed aggressor on the other, this may be very tricky to do safely. Follow any directions given. Holding your weapon in the universal "Please don't shoot me," position (as discussed in Weapons Retention and the Securing and Disabling Weapons Practical [Note: add photo or diagram]), placing your weapon on the floor with your foot on top of it, or placing a wastebasket upside down over a weapon and then sitting on it with your hands up are good default options. Once again, in these circumstances, it is often best to keep your weapon holstered until it is necessary to draw and fire it. This minimizes the chances of becoming a friendly-fire casualty. This is why present-from-hoster-and-fire dry-fire practice is necessary.
Be aware that it is possible for off-duty LEOs to arrive and enter the scene without contacting dispatch and therefore without being aware of your presence. This is bad and they should not do it, but there is little you can do to prevent it except try not to get shot. Law Enforcement may also go into tunnel vision where they may not register your attempts to identify yourself and may not recognize an ID on a lanyard. Holding or mentioning a weapon before it is necessary may be very dangerous.
Cold Zone
If you are in the Cold Zone at incident start or arriving in the Cold Zone (you were already deployed at a larger event when the incident started or you are called in for support), then you should first follow any orders received and coordinate with any response in progress. Communications should again default to Law Mutual Aid and MTAC, absent other instructions.
If there is no response in progress, then you are it. Your priorities should be:
Do not enter the Warm Zone or Hot Zone without orders. Without close coordination, you will become another potential victim, something else responders need to worry about, and potentially mistaken for the aggressor.