On the afternoon of March 22, 2021, a gunman opened fire in the parking lot and inside a King Soopers supermarket in Boulder, Colorado, killing ten people. The attack began shortly after 2:30 p.m. local time when the shooter, armed with a semi-automatic Ruger AR-556 pistol and a 9mm handgun, first shot a repairman in a parked van, then killed a person fleeing in the parking lot, and a third victim while entering the store. Witnesses described him wearing an armored vest. Boulder Police began receiving calls within minutes, and the first responding officers entered the store shortly after arriving. Officer Eric Talley, one of the first officers on scene, was shot and killed while approaching the gunman; police later said he was the last person killed in the attack. Additional officers continued to engage the gunman in a shootout between roughly 3:00 and 3:21 p.m. Police re-entered the store at 3:22 p.m., encountered the gunman, exchanged fire, and struck him in the thigh; he surrendered and was taken into custody at 3:28 p.m. using Talley's handcuffs. He had discharged his rifle 47 times.
Ten people were killed in total: seven inside the store and three outside, including Officer Talley, who had served with Boulder Police since 2010. A woman who fractured her back while escaping was the only other reported injury.
The suspect, identified as 21-year-old Ahmad Al Aliwi Al-Issa of Arvada, Colorado, was arrested after being shot in the leg and initially hospitalized before being transferred to the Boulder County Jail. He was charged with ten counts of first-degree murder and one count of attempted murder shortly after the shooting, with dozens of additional charges — including counts of attempted murder covering responding officers and civilians, and counts related to possession of high-capacity magazines — added in the following months. Investigators found Al-Issa was equipped with ten high-capacity magazines, which are illegal to possess in Colorado.
Legal proceedings were delayed for years due to competency disputes: courts found Al-Issa mentally incompetent to stand trial in December 2021 and again in April 2022, but in October 2023 a judge ruled he was competent following renewed evaluations. He pleaded not guilty by reason of insanity in November 2023. Trial began in August 2024, and on September 23, 2024, a jury found him guilty of ten counts of first-degree murder, 38 counts of attempted murder, one count of first-degree assault, and six counts of using a high-capacity magazine. He was sentenced the same day to ten consecutive life sentences without parole, plus 1,334 years; the death penalty was not sought because Colorado had abolished it before the shooting.
The attack renewed national debate over gun control, particularly regarding the legal classification of AR-15-style pistols equipped with stabilizing braces, and prompted new Colorado gun-storage and reporting laws.