Mass Shootings

There are two criminology definitions for public shootings, and they are very different:

Active Shooter Events (ASE): Where a person shoots at multiple people in public, though there may be no deaths. 1

Mass Public Shootings (MPS): Public shooting events where four or more people are killed. 2

Myth: Mass public shootings are increasing

MASS SHOOTINGS - Mass Public Shootings 1976 through 2011Fact: Over a 35-year period, the number of mass public shootings rose during the violence escalation decades of the 1970s and 1980, then leveled off, despite a growing population and greater availability for firearms (more people, more guns).

Special Note: The FBI created a study of what they labeled “active shooter” events from 2000-2013, but they merged both ASEs and MPSs. Combined, this data shows an increase whereas other studies that separate the two do not. But it must be noted that their study starts in the year 2000, which had an abnormally low number of public shootings (only one). 3

Myth: More people are dying in mass public shootings

MASS SHOOTINGS - Mass Public Shootings - Incidents and Deaths per capita - 1976 through 2011Fact: Though the raw number of mass public shootings has risen slightly over three decades, the number of people killed has fallen as a function of the population.

Fact: Mass public shooting deaths make up less than 1% of all gun homicides, making them a small part of the problem.

Myth: America has the highest rate of mass shootings in developed countries

MASS SHOOTINGS - Mass Shooting Deaths and Victims in Developed CountriesFact: On a per population basis, the United States ranks fourth behind three European countries 4 or eighth when a broader set of non-conflict countries are examined. 5

Myth: Easy access to guns creates an incentive for mass public shootings

Fact: At least 61% of mass public shooters showed signs of mental instability in the days, weeks or months before their massacres. 6 The rate might be higher because privacy laws prevent fully exploring the mental health history of some killers. Mental health is the determinant variable.

Myth: Guns in civilian hands are not good for stopping mass public shooters

Fact: One study shows that armed citizens responding to rampage killers result in 1/8th the number of casualties than when police intervene. 7 In other words, waiting on the police results in eight times as many people deaths and injuries.

Understanding conflicting reports on “mass public shootings”

There are several different studies concerning mass public shootings, which make different claims. The primary points of confusion come from:

  1. How the counting of such shootings is done
  2. How they define “mass public shooting”

Here are some of the studies that are circulated and critiques of them.

Mother Jones 8

  • This magazine report used media reports of mass shootings, which may not cover all such shootings and which lack criminological objectivity.
  • There appear to be some arbitrary omissions of events that do not fit their definition of a public shooting.
  • They only count “lone gunmen” events, and never the more common inner-city, gang-related multi-shooter episodes.
  • They include terrorist activities, such as the Fort Hood massacre.

Mother Jones concluded that mass shootings occur more frequently than several decades ago, and that the mass public shooting rate tripled since 2011.

James Alan Fox, Northeastern University criminologist 9

  • Based on police reports, which are uniform and comprehensive.
  • Includes all mass shootings, including those not in public, which defies the idea of a mass public shooting.

Concluded that mass shooting rates remain relatively stable over time.

Grant Duwe, Minnesota Department of Corrections, criminologist 10

  • Uses FBI Supplementary Homicide Reports for the core list, then media reports to provide details.
  • Includes only public events.
  • Excludes events related to other crimes (such as robberies gone wrong).

Concludes that mass public shootings declined from 1999 to 2011, then spiked in 2012 (the year of the Sandy Hook Elementary School shooting), then returned to the mean of previous years.

The one thing all of the studies agree upon is that
mass public shootings are statistically rare


  1. “One or more persons engaged in killing or attempting to kill multiple people in an area (or areas) occupied by multiple unrelated individuals. At least one of the victims must be unrelated to the shooter. The primary motive appears to be mass murder; that is the shooting is not a by-product of an attempt to commit another crime.” United States Active Shooter Events from 2000 to 2010, School of Criminal Justice, Texas State University, 2014 – published by the Federal Bureau of Investigation
  2. “Slaughter of four or more victims by one or a few assailants within a single event, lasting but a few minutes or as long as several hours”, Multiple Homicide: Patterns of Serial and Mass Murder, James Alan Fox, Jack Levin, Crime and Justice, Vol. 23, 1998
  3. A Study of Active Shooter Incidents in the United States Between 2000 and 2013, FBI, September 2013
  4. Mass Shootings: Media, Myths, and Realities, Jaclyn Schildkraut, H. Jaymi Elsass
  5. The facts shoot holes in Obama’s claim that US is only host to mass killings, John Lott, December 2015
  6. Mass Shootings: Maybe What We Need Is a Better Mental-Health Policy, Mother Jones, November 2012, analysis of 62 mass public shootings
  7. Auditing Shooting Rampage Statistics, Davi Barker, July 2013 and updated thereafter
  8. A Guide to Mass Shootings in America, Mother Jones, May 2014
  9. Mass Shootings in America: Moving Beyond Newtown, Homicide Studies, 2013
  10. Mass Murder in the United States: A History, McFarland, June 2007