Worst mass shootings in recent history

4 of 22: ** ADVANCE FOR SUNDAY AUG. 20 ** FILE **Members of the Edmond, Okla., police department and medical personnel remove one of those killed in a shooting spree Aug. 20, 1986 at the Edmond Post Office in Edmond, Okla. On Aug. 20, 1986, Patrick Henry Sherrill, an ex-Marine and small arms instructor for the Oklahoma Air National Guard, tucked two .45-caliber pistols into his postal satchel, locked the doors and systematically killed 14 people before killing himself inside a suburban Oklahoma City post office. (AP Photo/Steve Gooch) (AP Photo/ STEVE GOOCH)

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