Active shooter
Active shooter or active killer describes the perpetrator of a type of mass murder marked by rapidity, scale, randomness, and often suicide. The United States Department of Homeland Security defines an "active shooter" as "an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearms and there is no pattern or method to their selection of victims." Most incidents occur at locations in which the killers find little impediment in pressing their attack. Locations are generally described as "soft targets", that is, they carry limited  security measures to protect members of the public. In most instances, shooters commit suicide, are shot by police, or surrender when confrontation with responding law enforcement becomes unavoidable, and active shooter events are often over in 10 to 15 minutes. According to New York City Police Department (NYPD) statistics, 46percent of active shooter incidents are ended by the application of force by police or security, 40percent end in the shooter's suicide, 14percent of the time the shooter surrenders and, in less than 1percent of cases, the violence ends with the attacker fleeing. Terminology. In police training manuals, the police  response to an active shooter scenario is different from hostage rescue and barricaded suspect situations. Police officers responding to an armed barricaded suspect often deploy with the intention of containing the suspect within a perimeter, gaining information about the situation, attempting negotiation with the suspect, and waiting for specialist teams like SWAT. If police officers believe that a gunman intends to kill as many people as possible before committing suicide, they may use a tactic like immediate action rapid deployment. The terminology "active shooter" is critiqued by some academics. There have been several mass stabbings that have high casualty counts , for instance in Belgium (Dendermonde nursery attack) (1 adult and 2 infants dead), Canada (2014 Calgary stabbing) (5 adults dead), China (2008 Beijing Drum Tower stabbings) (1 adult dead), Japan (Osaka School Massacre and Sagamihara stabbings) (8 children and 19 sleeping disabled adults dead, respectively), and Pennsylvania (Franklin Regional High School stabbing) (no deaths). Ron Borsch recommends the term "rapid mass murder". Due to a worldwide increase in firearm and non-firearm based mass casualty attacks (including attacks with vehicles, explosives, incendiary devices, stabbings, slashing, acid attacks), Dr. Tau Braun and the Violence Prevention Agency (VPA) has encouraged the use  of the more accurate descriptor "mass casualty attacker" (MCA). Tactical implications. According to Ron Borsch, active shooters are not inclined to negotiate, preferring to kill as many people as possible, often to gain notoriety. Active shooters generally do not lie in wait to battle responding law enforcement officers. Few law enforcement officers have been injured responding to active shooter incidents; fewer still have been killed. As noted, more often than not, when the prospect of confrontation with responding law enforcement becomes unavoidable, the active shooter commits suicide. And when civilians—even unarmed civilians—resist, the active shooter crumbles. Borsch's  statistical analysis recommends a tactic: aggressive action. For law enforcement, the tactical imperative is to respond and engage the killer without delaythe affected orthodoxy of cumbersome team formations fails to answer the rapid temporal dynamics of active shooter events and fails to grasp the nature of the threat involved. For civilians, when necessity or obligation calls, the tactical mandate is to attack the attacker—a strategy that has proved successful across a range of incidents from Norina Bentzel (William Michael Stankewicz) in Pennsylvania and Bill Badger in Arizona (2011 Tucson shooting) to David Benke in Colorado. Taxonomy. The active shooter  incidents do not always meet the classification of a mass murder. Mass murders result when three or more individuals are killed. The definition of an active shooter does not require that victims are killed, only that they are injured or wounded by the act. Not all mass murderers are active shooters. Noting the similarities and differences among several types of mass murder will help to isolate and define what is meant by the term "active shooter". Mass murderers defy traditional criminal categorization. The goal of the mass murderer is neither to defend nor appropriate turf or territory, neither to initiate  himself into nor elevate his status within a criminal organization. The mass murderer does not kill for drugs or money. The serial killer is one kind of mass murderer. He claims many lives in multiple events across time. The events are discontinuous, punctuated by "a cooling-off period". By contrast, the active shooter claims many lives in a single event along a compressed frame of time. In practice, this appears to carry a corollary: broadly, the serial killer seeks anonymity; the active shooter, notoriety. Repetition through multiple events across time answers the pathology of the serial killer. Savage as they  are, his acts are not designed to excite publicity. The serial killer will conceal a corpse or bury evidence. He wants to kill again. By contrast, the active shooter seeks infamy through slaughter. He means to fuse his name forever to a place, a date, an event. Thus, his acts are designed to maximize publicity. Accordingly, he (generally) plans no escape. The serial killer murders at close quarters, delighting in experiencing the horror of his victims as he shares their space. In his distorted estimation, his victims "mean" something to him, and he may secure keepsakes from victims to memorialize  the "relationship". The active shooter also murders at close quarters. He delights in experiencing the horror of his victims as he shares their space. Crucially, however, while the victims of the serial killer "mean" something to him, to the active shooter they mean nothing. The active shooter moves rapidly from one victim to the next. Modell speculates that the contrast is rooted in the peculiar form of abuse each suffers. The serial killer is a victim of physical/sexual/emotional abuse. Such abuse is administered at length, over time, by those who, by relation or connection, should care for the  abused. The serial killer, after a manner, models this behavior. The active shooter is a victim of bullying. Though bullying may persist over time, it is delivered in discrete, relatively short-lived acts, often by multiple actors with no special relation or connection to the abused. The active shooter, after a manner, models this behavior. A portrait of the active shooter may be sharpened by contrasting him with another type of mass murderer, the ideological killer. The Oklahoma City bombing exemplifies the type: in 1995, Timothy McVeigh, who had ties to a disorganized militia movement, detonated a truck bomb in  front of the Alfred P. Murrah Federal Building in downtown Oklahoma City, and the resulting blast killed 168people while wounding680. The ideological killer is driven by adherence to ethico-political or religious orthodoxy. His actions are an expression of that orthodoxy. By contrast, while the active shooter may conceive of himself as "making a statement" of sorts, his motives appear more personal and desultory. Like the active shooter, the ideological killer plans multiple murders within the confines of a single event. But the active shooter seeks to experience the horror of his victims at close quarters. The ideological killer does  not. He kills at a distance. He plants explosive devices or takes up position as a sniper. Killing at a distance suits his primary motive—the expression of adherence to an abstract orthodoxy. For the ideological killer, victims are of incidental significance. He need not "know" them, as the serial killer must, nor experience their horror, as the active shooter must. For the ideological killer, abstraction is reality, the individual but a construct in an interminable struggle of dogmas. Since he is motivated by adherence to orthodoxy, the ideological killer typically seeks notoriety for his cause through carnage. While the  active shooter also seeks notoriety and while he also maps a careful plan of the event, there is a crucial difference in the pursuit. The ideological killer generally means to elude capture, to live beyond the event (as does the serial killer). The active shooter merges his identity with the event and sees nothing beyond. Integrating the elements elicited by comparison and contrast, the "active shooter (killer)" may be defined as a mass murderer who kills (or attempts to kill) at close quarters, in multiples, at random in a single, planned event. Causation. Accounts of why active shooters do what  they do vary. Some contend that the motive, at least proximately, is vengeance. Others argue that bullying breeds the problem, and sometimes the active shooter is a victim of bullying, directly or derivatively. Still others such as Grossman and DeGaetano argue that the pervasiveness of violent imagery girding modern culture hosts the phenomenon. Some argue that a particular interpretation of the world, a conscious or subconscious ontology, accounts for the phenomenon. They argue that the active shooter lives in a world of victims and victimizers, that all are one or the other. The ontology accommodates no nuance, no room between  the categories for benevolence, friendship, decency, nor indeed, for a mixture of good and bad. His interpretation of the world may grow out of or be fed by bullying or violent imagery (hence the common obsession with violent movies, books or video games), but it is the absolutist interpretation of his world that drives him both to kill and to die. In "The Psychology of the Active Killer", Daniel Modell writes that "The world conceived by the active killer is a dark dialectic of victim and victimizer. His impoverished ontology brooks no nuance, admits no resolution. The two categories, isolated  and absolute, exhaust and explain his world. And the peculiar logic driving the dialectic yields a fatal inference: in a world of victims and victimizers, success means victimization." Solutions. Many government installations, businesses, campuses have camera and sensor based security systems, some analog and, more recently, digital. Some also include formal command centers or at least are monitored by personnel in any organization. These provide very good forensic support in documenting an active shooter. However they offer only mixed results in the timely interdiction of an active shooter.