The Washington Post reported yesterday that there have been 355 mass shootings so far in 2015. Other mainstream media outlets such as The New York Times have also reported that mass shootings have surged to the extent that they occur at an average pace of around once per day.

While definitions of mass shootings vary based on who is calculating the statistics, the source that these articles are relying on to come to such a shocking number calculates the stat in a vastly different manner than the ways law enforcement agencies have traditionally evaluated them.

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The source of the stats is an unofficial, crowd-sourced compilation of news articles of shootings by members of the anti-gun Reddit sub-forum GunsAreCool which is also mirrored on the Mass Shooting Tracker website.

The Mass Shooting Tracker website states:

The most obscene incidents of gun violence usually do not make the mainstream news at all. Why? Because their definition is incorrect. The mainstream news meaning of ‘Mass Shooting’ should more accurately be described as ‘Mass Murder.’ The old FBI definition of Mass Murder (not even the most recent one) is four or more people murdered in one event. It is only logical that a Mass Shooting is four or more people shot in one event. Here at the Mass Shooting Tracker, we count the number of people shot rather than the number people killed because, ‘shooting’ means ‘people shot.’

Mass Shooting Tracker’s definition of a mass shooting as any gun violence event in which 4 people including the shooter are injured would include gang shootouts, robberies and drug deals gone wrong, suicide-by-cop incidents in which bystanders were inadvertently injured by police, and other incidents that deviate drastically from the Columbine and Sandy Hook type events that most Americans think of when talking about a mass shooting.

Mass Shooting Tracker included in its list of 2013 mass shootings a relatively harmless incident involving no serious injuries in which two boys aged 11 and 12 allegedly shot four people with BB guns.

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PolitiFact, who ranked Mass Shooting Tracker’s statistical assessment as “half true” noted, “Using 2013, the most recent year for which federal data is available, the Congressional Research Service found 25 mass shooting incidents — far less than the 363 counted by Mass Shooting Tracker.” The Congressional Research Service defines a mass shooting more narrowly as a gun violence incident in public in which 4 or more people are killed in a single event and excludes incidents in which the violence is a “means to an end such as robbery.”

PolitiFact’s Amy Sherman added, “Mass Shooting Tracker showed 294 mass shootings [in 2015] as of Oct. 1. About 122 of those incidents — or about 42 percent — involved zero fatalities.”

USA Today’s analysis of mass shootings in 2015, which defines them as incidents in which 4 or more people are killed by a firearm in a single event, found that there have been 29 cases so far this year.