Washington Navy Yard shooting

On the morning of September 16, 2013, Aaron Alexis, a 34-year-old civilian contractor with a valid access pass, entered Building 197 at the Washington Navy Yard — headquarters of the Naval Sea Systems Command (NAVSEA) — carrying a disassembled shotgun in a shoulder bag. After assembling the weapon in a fourth-floor bathroom, he opened fire at 8:16 a.m. in a cubicle area near the atrium, killing eight people on the fourth floor and two more on the third floor within minutes. He then moved to the first floor, where he shot and killed security officer Richard Ridgell and took his pistol, before fleeing further gunfire exchanges with responding officers and security personnel. A final victim was killed in an alleyway on the building's west side. In total, 12 victims were killed, including program manager Vishnu Pandit, who died later at George Washington University Hospital; all victims were civilian employees or contractors, none in the military. Three additional people were wounded by gunfire, including Metropolitan Police officer Scott Williams, and five more were injured overall.

Law enforcement from the D.C. Metropolitan Police Department and other agencies began arriving at 8:23 a.m. but struggled initially to locate Building 197. Confusion also arose over reports of a second shooting location and, later, over unconfirmed sightings of additional armed individuals, which were eventually ruled out. Alexis exchanged gunfire with officers on multiple occasions inside the building before being cornered in a third-floor cubicle area. At 9:15 a.m., officers Dorian DeSantis, Andrew Wong, and Carl Hiott engaged him in close-quarters gunfire; DeSantis shot Alexis in the head at 9:25 a.m., and Alexis's death was confirmed at 11:50 a.m.

Alexis was a former U.S. Navy petty officer, honorably discharged in January 2011 after multiple misconduct citations and prior arrests that never resulted in prosecution. He held a secret-level security clearance, later scrutinized after it emerged that his 2004 arrest involving a firearm had not been disclosed in his background investigation. In the weeks before the shooting, Alexis exhibited signs of significant mental distress, including a belief that he was being influenced by "extremely low-frequency electromagnetic waves," and sought treatment for insomnia at two medical facilities. He purchased a shotgun legally in Virginia two days before the attack after being denied a handgun sale due to out-of-state residency restrictions.

The shooting prompted a range of official and public responses: President Barack Obama ordered flags flown at half-staff, called for renewed gun control legislation, and later signed a bill authorizing a memorial. Defense Secretary Chuck Hagel ordered a review of security procedures at military facilities worldwide. Hewlett Packard fired the subcontracting firm that employed Alexis over its handling of his mental health issues. In February 2014, more than 170 responding law enforcement officers were honored, with Officers Scott Williams and Dorian DeSantis receiving valor awards. Building 197 was later renovated and reopened in 2015 under a new name.