The number of mass shootings in the US this year has already reached 366, as of November 14, according to the Gun Violence Archive's tally.

At least two people were killed and an additional three were injured in a mass shooting on Thursday afternoon at Saugus High School in Santa Clarita, California.

By the Gun Violence Archive's count, there have been more US mass shootings than days in 2019 so far.

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At least two people are dead and three injured after a mass shooting at Saugus High School in Santa Clarita, California.

The shooting occurred on Thursday afternoon after a 16-year-old gunman opened fire at his high school using a .45 semi-automatic pistol. According to authorities, the suspect shot himself in the head and is currently in "grave" condition. Capt. Kent Wegener of the Los Angeles County Sheriff's Office told reporters that the suspect's motivation was unclear, but that Thursday marked his 16th birthday.

According to the Gun Violence Archive, a nonprofit that tracks shootings in the US, there have been 366 shootings in 2019 so far. To put this into perspective, November 14 is the 318th day of the year, meaning that by their definition, the US has had more mass shootings than days in 2019.

Read more: There were 336 mass shootings in the US in 2018 — here's the full list

Americans are more likely to die from gun violence than many leading causes of death combined, with some 11,000 people in the US killed in firearm assaults each year.

The definition of 'mass shooting' varies

There is no broadly accepted definition of a mass shooting. The Gun Violence Archive defines a mass shooting as a single incident in which four or more people, not including the shooter, are "shot and/or killed" at "the same general time and location."

The government also doesn't have an official definition. In 2013, a report from the Congressional Research Service, known as Congress' think tank, described mass shootings as those in which shooters "select victims somewhat indiscriminately" and involve four or more deaths — a higher bar than the Gun Violence Archive's, as it doesn't take injuries into account.

Earlier in 2013, a federal mandate identified the threshold as three or more deaths.

According to data from the Gun Violence Archive, more than 34,000 people have died from gun-related violence in the US so far this year, and more than 25,000 others have been injured.

There have been 408 deaths from mass shootings alone since January, according to the GVA.

There have been 1,477 injuries from mass shootings since January.

Here's a complete list of the mass shootings, as defined by the Gun Violence Archive, that have occurred in the US so far in 2019:

You can view a report of any incident by visiting the list on the Gun Violence Archive's website.