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How Common Are Mass Shootings?

MINNEAPOLIS (WCCO) -- The massacre in Las Vegas is being called the deadliest mass shooting in modern U.S. history. To some, it seems like these tragedies happen more often. But do they?

How common are mass shootings? Good Question.

"They're happening at such an alarming rate that you can't even name all of them them in succession because they just blend together at some point," said one Minneapolis man Monday afternoon.

Hamline University Criminal Justice Professor Jillian Peterson says mass shooting data is quantified in many different ways, which makes it difficult to determine how often it happens.

"Mass shootings, they've been going on forever, but it depends on how you define them," she said. "It's hard to nail down how common they are."

The Congressional Research Service defines public mass shootings as when four or more people, not including the shooter, are killed in a public place. In 2016, there were four of those shootings where 65 people were killed at a mall, in a nightclub, on the streets, at a Cracker Barrel restaurant or a car dealership.

Others define mass shootings as when four or more people, not including the shooter, are killed or injured. Different researchers also include gang violence or domestic violence in their counts. If that were the measure, there were 248 mass shootings in 2016, according to Gun Violence Archive. That's one every day and a half.

According to one study from the University of Alabama, almost one-third of all mass shootings worldwide happen in the U.S. – which makes up 5 percent of the world's population.

"One reason that we're trying to build this big database and look at the histories of all these different mass shooters is to answer that question -- is this a case of untreated mental illness? Is this access to guns? Is this bullying?" says Peterson. "It's a way to be more scientific in thinking about intervention."

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