n Dec. 2, 2015: At least two heavily armed attackers opened fire at a social services center in San Bernardino, California, killing at least 14 people and wounding more than a dozen, authorities said. The shooters escaped, but police said one male and one female suspect were later killed in an exchange of gunfire with officers.

n Oct 1, 2015: A shooting at Umpqua Community College in Roseburg, Oregon, leaves 10 people dead and seven wounded. Shooter Christopher Harper-Mercer, 26, exchanged gunfire with police, then killed himself.

n June 17, 2015: Dylan Roof, 21, shot and killed nine African-American church members during a Bible study group inside the Emanuel African Methodist Episcopal Church in Charleston, South Carolina. Police contended the attack was racially motivated.

n May 23, 2014: A community college student, Elliot Rodger, 22, killed six people and wounded 13 others in shooting and stabbing attacks in the area near the University of California, Santa Barbara, campus. Authorities said he apparently shot himself to death after a shootout with deputies.

n 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.

n July 26, 2013: Pedro Vargas, 42, went on a shooting rampage at his Hialeah, Florida, apartment building, killing six people before being shot to death by police.

n Dec 14, 2012: In Newtown, Connecticut, an armed 20-year-old man entered Sandy Hook Elementary School and used a semi-automatic rifle to kill 26 people, including 20 first-graders and six adult school staff members, before killing himself.

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

n August 5, 2012: In Oak Creek, Wisconsin, 40-year-old gunman Wade Michael Page killed six worshippers at a Sikh Temple before taking his own life.

n July 20, 2012: James Holmes, 27, killed 12 people and wounded 70 in Aurora, Colorado, movie theater. He was sentenced to life in prison without parole.

n April 2, 2012: Seven people were killed and three were wounded when a 43-year-old former student opened fire at Oikos University in Oakland, California. One Goh was charged with seven counts of murder but psychiatric evaluations concluded he is unfit to stand trial.

– The Associated Press