Confronting the Active Shooter: Does Civilian Intervention Make a Difference?


            We tabulated data provided by the FBI on all active shooter (AS) incidents occurring in the United States from the years 2000-2018 and coded them based on whether or not civilians intervened during the incident. Our findings are consistent with the hypothesis that civilian intervention in active shooter incidents reduces the total number of casualties (killed and wounded) caused by the incident. Table 1. shows the average casualties (total killed and wounded) of incidents with vs. without civilian intervention. 

Table 1. 


A preliminary glance at data provided annually by the FBI and dating back to the year 2000 illuminates the alarming reality that instances of Active Shooter-type attacks in the United States are increasing in frequency year after year. (1) Although such incidents are extremely rare compared to other types of homicide (2) they tend to capture the public attention with their incomprehensible violence, catastrophic death tolls, and lasting, devastating effects on communities and survivors. In the wake of such tragedies, many experts have attempted to address the issue with improved training for law enforcement and civilians, especially schools. Few resources are available, however, that are based on a data-driven approach, and some efforts have had the unintended consequence of imparting substantial psychological harm on the communities they seek to aid by hosting realistic drills that involve children as young as eleven (3). 

A screenshot of a cell phone

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Source: FBI.Gov

The tactics utilized by law enforcement have evolved rapidly in the wake of the tragic events that occurred on April 20th, 1999, at Columbine High School in Columbine, Colorado, which left 13 dead and 21 injured. After Columbine, police officers swore to “never again wait for S.W.A.T.” and developed a strategy known as Rapid Response, which requires officers to respond immediately upon arriving at the scene of an active shooter scenario without waiting for backup (4). However, other studies have demonstrated that even an extremely hasty deployment of police resources still leaves “lag time” between the duration of the average active shooter incident and the arrival of police (5). This results in most active shooter incidents ending on the shooter’s terms before law enforcement even arrive on the scene. 

Recognizing the alarming gap between response time and incident duration, some efforts have been undertaken to examine incidents and suggest changes to facilities. Simultaneously, the law enforcement community continues to make efforts to expand and improve their tactics and reduce their deployment times while enhancing offer safety and scene communication (7). Regardless of the efforts of law enforcement and facility security specialists who are continually improving their internal procedures and suggestions to the public at large, the death toll from active shooter incidents continues to climb, in part due to the remaining gap between response time and incident duration. 


            Acknowledging that there is a significant gap between the average response time to active shooter incidents and the average incident duration, we set out to determine if the average casualties during incidents in which victims intervened to stop the shooter were significantly less than incidents in which victims waited for police response or incidents in which the shooter chose to cease his attack. Lieutenant Colonel (Retired) Dave Grossman, pre-eminent author of seminal works on the psychology of human violence (see On Killing, 1995) reminds us that active shooters are likely initiating attacks with the hope of encountering no resistance and are often stopped by any resistance at all, even verbal commands (8). We set out to determine if victim intervention actually correlated to a reduction in casualties during an active shooter incident. 

Testing and Methodology

            We relied on data provided by the FBI in the form of a catalog of incidents occurring between December 26th, 2000 and December 24th, 2018. (9) We tabulated each incident in a Google Spreadsheet by making columns for data provided by the FBI such as killed and wounded. We also coded a column called “incident result” and assigned each incident to a nominal category according to how the incident ended. Our categories were shooter suicide (SU), shooter suicide after police or civilian confrontation (SUAP, SUAC), killed on site by police or civilians (KOSP, KOSC), apprehended on site by police or civilians (AOSP, AOSC), apprehended by police after fleeing the scene (AASP) and the rare instance of shooter still at large (AT LARGE). We also annotated any incidents in which the FBI mentions victim or civilian attempts to confront the shooter that ultimately resulted in any of the above categories. We have created the following chart (figure 1) to indicate the average number of total casualties (killed and wounded) in comparison to the presence or absence of civilian or victim intervention. To determine if civilians intervened, we first examined our coding of all incidents and assigned AOSC and KOC to the category of civilian intervention, then added all incidents that ended in another result but were annotated as by us as having an element of civilian resistance. Our findings are presented below: 

We acknowledge the inherent limitations in our methodology that may have skewed our conclusions to favor one particular research outcome. For example, it is fair to assume that the conditions under which civilians often intervene are likely different from the conditions under which civilians do not, or cannot, intervene. For example, the October 2017 Las Vegas shooting left almost no chance for civilians to intervene because the shooter attacked from the 32ndfloor of a building with a dozen military-grade firearms. We emphasize caution when drawing the broad conclusion that the presence or absence of civilian intervention is a significant determiner of the casualty-outcome. Rather, what has been demonstrated by the results above is that a certain set of cofactors are either present or absent in Active-Shooter scenarios that make civilian intervention more or less likely. One reality is clear, however: when civilians end the killing, survivability goes up. 

Discussion and Recommendations

We conclude based on our analysis of all 277 incidents recorded by the FBI that in cases in which victims intervened in an attempt to stop an active shooter’s rampage, the outcome was fewer total casualties (killed and wounded). Incidents in which no civilian intervention occurred had an average casualty rate of 9.71, while those in which civilian intervention occurred had an average casualty rate of 3.91. We find this consistent with the theory presented by Grossman & Fairbairne that active shooters are often able to be stopped by any confrontation whatsoever, and also consistent with the urgent warning raised by Ergenbright & Hubbard that the lag time which elapses between the average incident duration and average police response leaves room for the killing to continue unabated. Recognizing the impetus for a victim-driven response to active shooter scenarios, it is reasonable for us to conclude that facilities with more hardened doors, tools for barricade, and basic training for facilities staff on how to confront active shooters, even if unarmed, could potentially lead to the reduction in harm caused by active shooters. 

            More research is needed to determine under what conditions civilians are afforded the opportunity to participate in their own survival. Ergenbright and Hubbard provided excellent foundational evidence that infrastructure upgrades can improve the ability of victims to protect themselves during the critical lag-time during which police are rapidly trying to reach victims. A team of researchers could begin their inquiry into this discussion with a new principle question: “under what conditions do civilians and victims tend to intervene in active-shooter scenarios?” 


The National Tactical Officers Association reminds us in a document meant to prep departments on preparation for active shooter scenarios that such an event will occur under extremely suboptimal circumstances and many common police protocols related to officer safety will have to be, essentially, thrown out of the window (10). NTOA writes that active confrontation and ingress into a building containing a shooter, without a plan, is the last option for even a S.W.A.T. team, the highly specialized unit most prepared for high-stress incidents. With the advent of the rapid response protocol, regular police officers are expected to utilize a S.W.A.T. team’s last option as their first option, entering into the kinetic environment caused by an active killer in a confined public space with the aim of saving lives. Police officers are sworn defenders of the public and thus asking them to commit such an act of heroism is, although auspiciously courageous, part and parcel of the job in the unpredictable environment of the 21st century. Under no circumstances could we ever expect school administrators, civilians in public spaces, or other innocent victims to respond with the same courage to an active shooter, and yet we see that police rarely arrive in time to make a difference when a hail of bullets is unleashed. It is essential to recognize, then, that timely civilian intervention has and will continue to save lives, and to focus future plans meant to confront the growing threat of active shooters with the recognition that civilians, and their training, preparation, and integration into the threat-mitigation process, can substantially reduce the threat. 


  1. “Quick Look: 277 Active Shooter Incidents in the United States,” 2000-2018. FBI, 2018.
  1. Bonnie BerkowitzChris AlcantaraDenise Lu, “The Terrible Numbers that Grow with Each Mass Shooting.” The Washington Post, Nov. 2019.
  1. Elizabeth Williamson, “When Active Shooter Drills Scare the Children they Hope to Protect.” The New York Times, Sep. 2019.
  1. “Rapid Deployment as a Response to an Active Shooter Incident” Illinois State Police Academy, 2003. 
  1. Ergenbright, Charles E., & Hubbard, Sean K. “Defeating the Active Shooter: Applying Facility Upgrades in Order to Mitigate the Effects of Active Shooters in High Occupancy Facilities” Jun. 2012, Naval Postgraduate School, M.S. Dissertation 
  1. Ibid. 
  2. “Tactical Response and Operations Standards for Law Enforcement Agencies” National Tactical Officers Association (NTOA), Apr. 2018.
  3. Fairburn, R., & Grossman, D., “Preparing for School Attacks.” The Police Marksman, Nov/Dec 2006.
  4. “2000 to 2018 Active shooter incidents” FBI, 2018.
  1. 10.  “Tactical Response and Operations Standards for Law Enforcement Agencies” National Tactical Officers Association (NTOA), Apr. 2018


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