On Feb. 25, 15 people at a Kansas factory were shot, three of them killed, by a co-worker whom police say had also shot two other people as he drove toward the facility. The shooting at Excel Industries in Hesston, Kansas, was at least the fourth workplace shooting in the United States in the past 12 months alone.

Here are some questions and answers about workplace shootings:

WHAT OTHER WORKPLACE SHOOTINGS HAVE TAKEN PLACE IN THE PAST 12 MONTHS?

Aug. 26, 2015: Alison Parker and Adam Ward of Roanoke, Virginia, TV station WDBJ were fatally shot by former employee Vester Lee Flanagan II during a live broadcast. The person they were interviewing was wounded. Flanagan fatally shot himself after a police chase.

Feb. 23, 2015: An employee of armed security company Shields Business Solutions in Moorestown, New Jersey, opened fire on a co-worker inside the business before fatally shooting himself outside amid what police described as an “ongoing domestic situation.” Moorestown Police Lt. Lee Lieber said Edgar Figueroa killed himself after shooting Melvin Nieves four times.

Feb. 12, 2015: Truck driver Jeffrey DeZeeuw got into an argument over a delivery with a supervisor at a Sioux Steel Co. location known as ProTec, in Lennox, South Dakota. DeZeeuw later returned, fatally shot the supervisor and wounded worker Kathy Steever. He also injured another employee, Brian Roesler, who confronted DeZeeuw and is credited with likely preventing more injuries or deaths. DeZeeuw then killed himself.

WHAT WAS ONE OF THE EARLIEST WORKPLACE SHOOTINGS?

On Sept. 14, 1989, Joseph Wesbecker, a disgruntled worker wracked with rage and mental illness, brought an AK-47 into the Standard-Gravure printing plant in Louisville, Kentucky, and killed eight employees before killing himself. It’s widely described as one of the first workplace shootings in the United States.

WHAT OTHER WORKPLACE SHOOTINGS HAVE OCCURRED OVER THE PAST 5 YEARS?

Sept. 23, 2014: Rayon Bartley shot his co-worker Jose Raul Cardenas-Ramirez at Renaissance Ross Bridge Golf and Resort Spa in Hoover, Alabama. Investigators said Bartley was fired and returned the next day to kill Ramirez. He was later arrested and charged with murder.

Sept. 23, 2014: Fired UPS employee Kerry Joe Tesney killed two supervisors, Doug Hutcheson and Brian Callans in Birmingham, Alabama, before killing himself.

Aug. 1, 2014: Anthony DeFrances, an executive at the Chicago company Arrowstream, shot the company’s CEO Steven Lavoie twice, and then turned the gun on himself. DeFrances had been demoted from his position as chief technology officer. Lavoie died several months later from his injuries.

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

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

Aug. 24, 2013: Longtime employee Hubert Allen Jr., 72, targeted several of his former co-workers at Pritchett Trucking in Lake Butler, Florida, killing three people, including company founder Marvin Pritchett, and wounding two others before killing himself.

June 13, 2013: St. Louis businessman Ahmed Dirir fatally shot all three of his employees at his home health care agency before killing himself.

Sept. 27, 2012: Andrew Engeldinger, who had just been fired from Accent Signage Systems in Minneapolis, fatally shot six people, including the company’s founder. He also wounded two others before killing himself.

Aug. 31, 2012: Two young employees at a Pathmark supermarket in Old Bridge Township, New Jersey, were gunned down by co-worker Terence Tyler, who then fatally shot himself.

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 by police on a crowded street. Stray and ricocheting police bullets injured nine people nearby.

Feb. 26, 2012: At the Immigration and Customs Enforcement’s office in Long Beach, California, 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 killed Garcia. Kozak survived.

Jan. 13, 2012: At a North Carolina lumber warehouse, Ronald Dean Davis fatally shot three co-workers and critically wounded another before going home and fatally shooting himself.

Dec. 16, 2011: An employee of Southern California Edison, Andre Turner, shot and killed two company managers and critically injured two other colleagues in a utility office in Irwindale, before fatally turning his gun on himself.

Oct. 6, 2011: A truck driver opened fire at a Lehigh Southwest Cement plant in Cupertino, northern California, killing three co-workers and injuring six others. Gunman Shareef Allman led police on a 27-hour manhunt before fatally shooting himself in the head during a standoff.

Associated Press News Researcher Jennifer Farrar contributed to this report.

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