On March 22, 2021, a mass shooting occurred at a King Soopers supermarket in Boulder, Colorado, United States.

On August 23, 2023, prosecutors announced that Al-Issa was mentally competent to stand trial;[10] a judge ruled as such on October 6 of that same year.

The gunman then walked towards the store; along the way, he killed another person in the parking lot who was trying to flee, shooting him multiple times.

[23] At 2:33 p.m., the Boulder Police Department began receiving calls of a person with a "patrol rifle" in the area and shots being fired.

[21][22] At 2:34 p.m., a Boulder Police dispatcher provided an initial description of the gunman as "a white male, middle-aged, dark hair, beard, black vest, short-sleeved shirt.

[17] When a team of ten officers from multiple agencies reentered, they encountered the gunman at one of the aisles within 20 seconds of their entry; he fired at them at least twice.

[2][33][52] He pleaded guilty to an assault charge in relation to the incident, received a year of probation, and was ordered to undergo 48 hours of community service.

[50] Boulder police clarified in a news conference on March 26 that they believed the AR-556 pistol was the only weapon used by the suspect during the shooting and added that he also had a 9mm handgun with him.

[47] Al-Issa expressed on Facebook and to his former high school wrestling teammates that he believed he was being targeted for harassment due to racism and Islamophobia.

[33][52][53] According to SITE Intelligence Group, "there was no indication on his Facebook account that suggested radical views of any kind, whether it be Islamist, anti-Trump, or anything else.

[50][52][57] The Boulder County District Attorney waited to reveal more information about Al-Issa's motives while the FBI and other agencies were investigating the case, to help ensure a fair trial.

U.S. Representative Joe Neguse, whose district includes Boulder, spoke at the vigil about curbing gun violence.

[72] University of Colorado Boulder professor and poet Khadijah Queen also spoke at the vigil, which was organized by gun violence prevention group Moms Demand Action.

Dignitaries included King Soopers president Joe Kelly, Mayor Aaron Brockett, and Polis, a Boulder resident.

[5][87] The Boulder District Attorney said that there was no evidence the magazines were sold or obtained illegally, but that Al-Issa broke laws by having them on his person and in his vehicle.

[105] Based on doctors' assessments, District Attorney Michael Dougherty expected the defendant's competency will improve, that he will be able to stand trial and justice will be served.

[16][93][12] Al-Issa legally purchased a Ruger AR-556 pistol on March 16 at a local gun shop in Arvada that used Colorado's universal background check law, even though he was previously convicted of third-degree assault, a misdemeanor with a sentencing maximum of 18 months in county jail.

Federal firearms laws only prohibit weapons purchases for those convicted of a felony, or a misdemeanor with a prison term of over 24 months.

"[114] At the national level, President Joe Biden called for an immediate ban on assault weapons; other Democratic politicians echoed his sentiments, including U.S.

[115][116] Biden also urged that loopholes be closed in the background check system and praised Officer Eric Talley, who was killed in the shooting, for his heroism.

[117] In an interview with CBS This Morning, Vice President Kamala Harris responded to the mass shootings by discussing the need for gun reform legislation.

[121] Satirical news site The Onion republished its 'No Way To Prevent This,' Says Only Nation Where This Regularly Happens article the day following the shooting.

[126] On April 8, Biden announced an executive order in response to the Boulder shooting that called for the U.S. Justice Department to clarify within 60 days whether a gun marketed with a stabilizing brace, such as the Ruger AR-556, effectively turns a pistol into a short-barreled rifle.

[127] On June 7, the Justice Department announced that Attorney General Merrick Garland signed proposed rule 2021R-08, "Factoring Criteria for Firearms with Attached 'Stabilizing Braces,'" to make this clarification by September 8.

[129] On January 13, 2023 the U.S. Justice Department finalized its ruling to close a loophole that allowed pistols to be converted into short-barreled rifles through the use of attached stabilizing braces, such as the gun used in the Boulder shooting.

[130] The ruling with additional regulations was announced by Attorney General Merrick Garland and ATF Director Steve Dettelbach.

[144] Before officers arrived on the scene, a police dispatcher described the active shooter as a "white male"; the suspect's actual identity was released around 18 hours after the shooting.

[36] Deborah Richardson, ACLU of Colorado's executive director, said that early assumptions made by law enforcement about Al-Issa were affected by the perception that he was white.

[145] On March 22, before the suspect's identity was made public, the Indian American race-and-inclusion editor of USA Today's Sports Media Group, Hemal Jhaveri, reacted to the shooting on Twitter, inaccurately saying, "It's always an angry white man.

By March 26, Jhaveri had been fired by USA Today, with her attributing this to the tweet and its promotion by "several high profile alt-right Twitter" users "as an example of anti-white bias and racism against whites".