On Dec. 2, 2015, 14 people were reported dead and an estimated 14 hurt in an attack at the Inland Regional Center in San Bernardino, California, a state-run facility that provides services to people with developmentally disabled people and trains social workers who care for them. The killers remained on the run Wednesday afternoon.
On Aug. 20, 1986, postman Patrick Henry Sherill killed 14 postal workers in Edmond, Oklahoma, and then killed himself with a shot to the head. The rampage came a week after two supervisors reprimanded him for lousy performance.
On April 20, 1999, students Eric Harris, 18, and Dylan Klebold, 17, killed 12 other students and a teacher at Columbine High School in Littleton, Colorado. Two dozen were injured. They then killed themselves in the school's library. In journal entries, the high school seniors had written about a desire to imitate events such as the Oklahoma City bombing.
On Nov. 5, 2009, Mad. Nidal Malik Hasan, 39, killed 13 people and injured 32 others at Fort Hood, Texas. The massacre prompted the Army to come up with a list of 78 recommendations for Fort Hood to identify the potential for violent behavior among its soldiers. Hasan has been sentenced to death.
On April 3, 2009, in Binghamton, New York, 41-year-old Jiverly Wong, an immigrant, killed 13 people and injured four others at an immigrant services center before killing himself. President Obama called the shootings "an act of senseless violence."