204 mass shootings in the United States so far in 2015, crowd-sourced tracker says

Scroll through the gallery for a timeline of some of the deadliest mass shootings in U.S. history. Scroll through the gallery for a timeline of some of the deadliest mass shootings in U.S. history. Photo: File Photo: File Image 1 of / 42 Caption Close 204 mass shootings in the United States so far in 2015, crowd-sourced tracker says 1 / 42 Back to Gallery

A mass shooting that killed three people Thursday at a movie theater in Louisiana is only the latest in a string of more than 200 such shootings this year, a website that tracks U.S. gun deaths says.

Forty U.S. states this year have seen mass shooting incidents "when four or more people are shot in an event, or related series of events, likely without a cooling off period," according to the crowd-sourced website Mass Shooting Tracker.

The total number of shootings in 2015 under that definition stands at 204, the website says.

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Of course, not all of those shootings have been as deadly as the shooting in Louisiana on Thursday evening.

Or, the July 16 shooting Muhammad Youssuf Abdulazeez at two military installations in Chattanooga, Tennessee, that left four Marines and one Navy sailor dead.

Or, the June 17 fatal shooting of nine people by 21-year-old Dylann Storm Roof at a historic black church in Charleston, South Carolina.

But, not all analysts use the same definition when describing a mass shooting, Vox reports: the Harvard School of Public Health defines them as shootings that take place in public and kill four or more people that don't involve domestic, drug and gang violence.

Meanwhile, The Stanford Geospatial Center says a mass shooting "involves an active shooter who shot 3 or more people in a single event."

Scroll through the above gallery for a timeline of some of the deadliest mass shootings in U.S. history.

jfechter@mySA.com

Twitter: @JFreports