The year began with the Monterey Park shooting, and the shooting spree in Half Moon Bay followed two days later. The shooting at Michigan State University occurred not long after, and now, at the time of this writing, the headlines still carry fresh details of the senseless act of violence that took place at the Covenant School in Nashville.
If the emerging trend of the last few years is any indication, 2023 will bring with it more incidents like these, along with more reminders to not become desensitized to them.
Statistics released in 2022 by the Federal Bureau of Investigation (FBI) indicate an alarming rise in active shooter incidents.
This includes mass shootings, those unthinkable outbursts of violence that engender nationwide grief, outrage, and confusion as shocked citizens wonder where and when the next event will occur.
The most up-to-date active shooter facts and mass shooting statistics from online databases and trackers shed some light on just how frequent these events are and why casualty numbers have become so high.
Table of Contents
How Are "Active Shooter Incidents" Defined?
The FBI defines an active shooter incident as "one actively engaged in attempting to kill people in a populated area." The ongoing nature of the incident is implicit in the phrase "individual actively engaged," and any response made by law enforcement or citizens could impact the event's outcome.
As the FBI defines it, an event is deemed an active shooter incident regardless of whether the shooter succeeds in carrying out their intentions to kill or harm, and an event with zero casualties is still defined by the FBI as an active shooter event if it meets the criteria for this definition.
In addition to firearms, active shooters occasionally attempt to use other weapons, such as explosive devices, to injure or kill people and/or to impede law enforcement and emergency responders.
FBI Report: Active Shooter Incidents in the United States in 2021
In determining which forms of active shootings to include in their most recent report on the topic, the FBI considered situations:
that occurred in public places
that occurred in multiple locations
in which the shooter's actions did not result from another criminal act
that resulted in a mass killing (defined on the federal level as "three or more killings in a single incident")
appearing to indicate a spontaneous decision by the shooter
in which the shooter had an apparent method behind their search for potential victims
in which the shooter apparently aimed to harm or kill people rather than damage buildings or objects
The FBI excluded any gun-related violence found to result from:
gang or drug violence
disputes contained to residential or domestic areas
controlled barricade or hostage situations
crossfire that was a byproduct of other criminal acts
an action that did not appear to have endangered others
Active Shooter Incidents: Latest Statistics
Total Number of Active Shooter Incidents
According to data compiled by the Federal Bureau of Investigation, the number of active shooter incidents occurring per year is on the rise.
Thirty of such incidents were recorded in 2019 -- no significant change from 2018 and 2017.
Between 2019 and 2020, however, this number jumped by 33%, with 40 occurring in the first year of the COVID-19 pandemic. In 2021 this number soared to 61, a distressing rise of 52.5%.*
*Twelve of the 61 active shooter events of 2021 met the FBI's definition of a mass killing.
Where Most Active Shooter Incidents Occur
Places of commerce and open spaces were the two most common locations for active shooter incidents in 2021. Of the 61 active shooter incidents that year, the majority (32) took place in commerce areas (e.g. workplaces), and 19 incidents took place in open spaces. One to three incidents each occurred in other types of locations.
Location types and respective numbers of active shooter incidents in 2021
Roving Active Shooters: An Emerging Trend
In their report, the FBI noted an emerging trend in 2021 of roving active shooters, gunmen attempting to kill people in multiple locations either in a single day or across several.
Resolutions of Active Shooter Incidents
Most active shooter incidents resolve in one of several ways:
A firefight occurs between the shooter and law enforcement.
The shooter commits suicide.
Armed citizens engage the shooter in a firefight and neutralize the perpetrator.
Unarmed citizens restrain the shooter.
Resolutions of the 61 Active Shooter Incidents of 2021
Shooter was apprehended: 30
Shooter was killed by law enforcement or armed citizens: 19*
Shooter committed suicide: 11
Shooter is still at large: 1
*One shooter's death occurred in a vehicle crash and does not fit any of the resolution categories as the FBI defines them.
2021 saw an increase in citizens engaging with the active shooter and bringing the incident to an end. Four of such incidents occurred in that year.
In two events, the shooter was detained until the arrive of law enforcement officers. In two others, the shooter was shot and killed by armed citizens.
Number of Active Shooter Casualties (Excluding Shooters)
From 2017 to 2021, a total of 1,624 people were either killed or injured from active shooter incidents.
The highest casualty numbers by far occurred in 2017 due to the Route 91 Harvest Festival shooting in Las Vegas, in which 143 people lost their lives and another 591 were injured.
In 2020, the year of the 33% jump in active shooter incidents, the lowest figures for deaths (38) were recorded over the period.
How Are "Mass Shootings" Defined?
Once casualties occur from an active shooter incident, it may or may not be defined as a "mass shooting" by media sources or online trackers of such incidents.
This is because there currently exists no official definition of "mass shooting," and the FBI itself does not specifically define the phrase. This results in significantly different figures for these events among various platforms and media organizations.
Mass Shooting Incidents - Latest Statistics
When reviewing statistics on incidents that qualify as mass shootings, it is helpful to be aware of the methodology the source uses in deciding whether an incident is to be designated as such.
Reported numbers will be much lower from trackers or databases with stricter thresholds for casualty numbers, shooting location types, or other criteria.
Mass Shooting Databases -- Criteria for Inclusion and Recent Numbers
Mother Jones defines mass shootings as "indiscriminate rampages in public places" that result in the killing of three or more people with the exception of the perpetrator.
For inclusion in their extensive database of mass shooting incidents, the publication excludes events stemming from gang violence or armed robbery or events in which the perpetrator is unidentified.
With its exclusion of shootings in these contexts and its consideration of only fatality numbers (as opposed to considering injury numbers), Mother Jones uses one of the most restrictive definitions. 
Mother Jones's Numbers of Mass Shootings Per Year
The Violence Project's mass shooter database defines a mass shooting as an incident in which four or more victims are killed with firearms within a single event, with the exception of shooters.
At least some of the deaths took place in a public location or locations nearby. Excluded from the database are murders attributable to "underlying criminal activity or commonplace circumstance," such as through armed robbery or other violent confrontation.
The Violence Project's Numbers of Mass Shootings Per Year
Gun violence prevention organization Everytown for Gun Safety defines a mass shooting as "any incident in which four or more people are shot and killed, excluding the shooter."
Both public and private settings are included in their definition, as is gun violence stemming from gang or other criminal activity.
Everytown for Gun Safety's Numbers of Mass Shootings Per Year
*The research on shootings done by Everytown for Gun Safety examines the period between 2009 and 2020.
Gun Violence Archive
The non-profit Gun Violence Archive defines mass shootings as the shooting of four or more victims, not including the killing or injuring of any shooter.
Rather than focusing solely on number of deaths, the platform considers the number of individuals shot in the incident, regardless of the severity or outcome of their injuries.
Gun Violence Archive's Numbers of Mass Shootings Per Year
Mass Shooting Tracker
The crowdsourced Mass Shooting Tracker, often cited by The New York Times, The Washington Post, CNN, MSNBC, and The Economist, uses the least restrictive definition for mass shooting among these five, defining the event as an incident in which "four or more people are shot in a single shooting spree."
This may include a self-inflicted injury to the perpetrator, their death by suicide, or the shooting or killing of the perpetrator by an armed citizen or member of law enforcement.
It may also include any civilians near the gunman who are accidentally shot by officers attempting to neutralize him or her.
Mass Shooting Tracker's Numbers of Mass Shootings Per Year
Types of Weapons Used in Mass Shootings
Handguns are the most common weapon used in mass shootings. According to The Violence Project, from 1966 to 2020, 80% of mass public shootings with four or more victims involved the use of at least one handgun.
Firearms known as semi-automatic assault weapons are the second most common weapon used in mass shooting incidents, at just under 28%.
The term "semi-automatic" refers to any gun, including handguns, that automatically loads its next bullet. An "assault weapon" is a non-official term generally referring to weapons originally used by the military. 
In fact, a wide-angle look at all shooters from The Violence Project database (spanning 1966 to 2020) reveals an increasing trend of mass shooters using semi-automatic assault weapons.*
From 2012 to 2020, nearly 43% of public mass shootings with at least four victims involved the use of at least one of these weapons.
When used to kill people in a populated area, semi-automatic assault weapons produce staggering casualty numbers.
Eight of the top 10 deadliest U.S. mass shootings of the last century involved the use of a semi-automatic assault weapon, including the school shootings at Sandy Hook in Newtown, Robb Elementary in Uvalde, and Marjorie Stoneman Douglas High School in Parkland.  
*The Violence Project defines a semi-automatic assault weapon as any semi-automatic gun that can accept a detachable ammunition magazine and which has one or more additional features considered useful in military and criminal applications but not necessary for sports or self-defense, e.g. a folding, telescoping or thumbhole rifle stock. This is consistent with the Federal Assault Weapons Ban of 1994. 
The increasing number of active shooter incidents combined with the effects of the pandemic, political division, economic challenges, and other difficulties, has Americans under an unprecedented amount of collective stress, according to the American Psychological Association.
Fear of mass shootings contributes to one in three American adults avoiding certain types of frequently targeted locations, and a majority of teenagers report feeling very anxious about an active shooter situation taking place while they are at school and how to react appropriately if such an incident occurs.
However, numbness, especially in the face of large victim numbers, is another common response to the seemingly endless stream of gun violence in the news.
Though cancer or heart disease is more likely than a firearm to take the life of the average American, we are still 10 times more likely to die from gun violence than citizens of other wealthy nations.
And then there's this troubling new statistic from the Center for Disease Control: Firearm-related injuries are now the leading cause of death for children and teenagers in the United States, overtaking car accidents in 2020. Ours is the only wealthy nation in the world where guns are even in the top 4 causes of death for young people. 
No matter the definition one uses to define a mass shooting, the statistics indicate that this phenomenon isn't on its way out. The frequency of people entering public populated areas with a firearm and an intention to kill is troublingly high here, and it shows no signs of abating.
This article was written with the aid of the latest statistics and resources. To the best of our knowledge, the data presented here is accurate at the time of this writing. However, gun violence in the U.S. is ever evolving.
For the latest information regarding active shooter incidents, mass shootings, and how to react appropriately if such an incident occurs, we recommend the articles and studies referenced here in addition to law enforcement agencies and associated websites.