The 12th deadliest shooting occurred in 2013, when a gunman opened fire inside the Washington Navy Yard in Washington, D.C, killing 12 people. Two separate shootings—one in Binghamton, New York, another in Fort Hood, Texas, both in 2009—each claimed the lives of 13 people, sharing the title of eighth most deadly. The country endured its deadliest shooting in history in 2007, when a senior at Virginia Tech killed 32 people and wounded 17 others.
Public health researchers at Harvard University and Northwestern University have confirmed that mass shootings are becoming more frequent, and the San Bernardino shooting is the latest. There have now been 355 this year alone, including all incidents in which at least four people, including the gunman, are wounded by gunfire.