TAMPA, Fla (WFLA) – More than 30 people were killed in two mass shootings over the weekend and, as of Monday, the death toll was still rising.

With information flooding the internet about mass shootings, 8 On Your Side is showing you the major difference in the many counts of mass shootings.

There are two generally accepted definitions of a mass shooting. As part of its Mass Shootings in America data project, Stanford University defines a mass shooting as “three or more shooting victims (not necessarily fatalities), not including the shooter. The shooting must not be identifiably gang, drug or organized crime-related. “

In 2013, President Barack Obama issued a federal mandate lowering the definition of a mass shooting from four, to three victims.

The FBI, however, does differentiate between a mass murder and a serial murder by saying “the time period between murders separates serial murder from mass murder.”

For a mass public shooting, these tragedies have to meet a larger set of requirements.

According to the Congressional Research Service’s Mass Murder with Firearms: Incidents and Victims, a mass public shooting means “a multiple homicide incident in which four or more victims are murdered with firearms, within one event, in at least one or more public locations, such as, a workplace, school, restaurant, house of worship, neighborhood or other public setting.”

According to the report, which analyzed FBI data, mass shooting incidents and victim counts fluctuated from year to year.

Mass shootings victims

Here’s a look at the number of mass shooting victims in the U.S. over the past nine years. Hover over the bar to see the numbers.


Source: Mother Jones

That study, which also conducted a study of mass public shootings between 1970 and 2013, showed on average:

  • 1 incident per year during the 1970s, with 5.5 victims murdered, 2 wounded per incident
  • Nearly 3 incidents per year during the 1980s, with 6.1 victims murdered, 5.3 wounded per incident
  • 4 incidents per year during the 1990s, with 5.6 victims murdered, 5.5 wounded per incident
  • 4 incidents per year during the 2000s, with 6.4 victims murdered, 4 wounded per incident
  • 4 incidents per year between 2010 and 2013, with 7.4 victims murdered, 6.3 wounded per incident

Mass public shootings average

Take a look at the average number of mass public shootings in the U.S. between 1970 and 2013. Hover over the bar to see the numbers.


Source: Congressional Research Service

This federal data shows a slight, but steady increase in the prevalence and deadliness of “mass public shootings.”

As of Monday, the United States has seen 56 mass shootings in 2019 – which include mass public shootings – averaging out to 1.2 shootings each day. In those shootings, 1,057 people were shot. Of those shot, 283 have died.

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