While those larger datasets of multiple-victim shootings may be useful for studying the broader problem of gun violence, our investigation provides an in-depth look at the distinct phenomenon of mass shootings—from the firearms used to mental health factors and the growing copycat problem.
We adopted that baseline when we gathered data in 2012 on three decades worth of cases.(It bears noting that there have been many similar indiscriminate gun rampages with fewer fatalities that would otherwise be included in our dataset.) In January 2013, a mandate for federal investigation of mass shootings authorized by President Barack Obama lowered that baseline to three or more victims.created the first open-source database documenting mass shootings in the United States.Our research has focused on indiscriminate rampages in public places resulting in four or more victims killed by the attacker.
We exclude shootings stemming from more conventional crimes such as armed robbery or gang violence.
Other news outlets and researchers have published larger tallies that include a wide range of gun crimes in which four or more people have been either wounded or killed.