Below is a list of fatal workplace shootings since January of 2012.

— Apr. 2, 2014: At Fort Hood, Texas, three soldiers died and 16 others were wounded in a shooting rampage by another soldier, Army Spc. Ivan A. Lopez, who then killed himself.

— Sept. 16, 2013: Aaron Alexis, a mentally disturbed civilian contractor, shot 12 people to death at the Washington Navy Yard before he was killed in a police shootout.

— Aug. 24, 2013: A 72-year-old man went on a shooting rampage in Lake Butler, Florida, targeting several of his former co-workers at Pritchett Trucking. Former longtime employee Hubert Allen Jr. tracked down and killed three people, including company founder Marvin Pritchett, and injured two others before killing himself.

— June 13, 2013: A St. Louis businessman, Somali immigrant Ahmed Dirir, fatally shot all three of his Somali employees at his home health care agency before killing himself with the same gun.

— Sept. 27, 2012: In Minnesota's deadliest workplace killing spree, Andrew Engeldinger, who had just been fired, pulled out a gun and fatally shot six people, including the company's founder. He also wounded two others at Accent Signage Systems in Minneapolis before committing suicide.

— Aug. 31, 2012: Two young employees at a Pathmark supermarket in Old Bridge Township, New Jersey, were gunned down and killed by co-worker Terence Tyler, who then committed suicide by shooting himself in the head.

— Aug. 24, 2012: Jeffrey Johnson ambushed and killed a former co-worker outside the Empire State Building in New York City, and was then shot to death himself by police officers on a crowded midtown street. Stray and ricocheting police bullets injured nine nearby civilians, none fatally.

— Feb. 26, 2012: A wild double-shooting at the Immigration and Customs Enforcement's Long Beach, California office occurred after Kevin Kozak, the second-in-command for the agency's Los Angeles region, turned down a transfer request by Ezequiel Garcia, who then shot him six times. Another agent rushed into the room and killed Garcia. Kozak survived.

— Jan. 13, 2012: In a shooting rampage at a North Carolina lumber warehouse, Ronald Dean Davis killed three co-workers and critically wounded another before going home and fatally shooting himself in the head.