[10] Located about 30 miles (48 km) southeast of San Jose and the Silicon Valley area, Gilroy is home to about 60,000 people, and the city is a major producer of garlic.

[7] As Gilroy's top fundraising event, the Garlic Festival was staffed with volunteers to raise money for nonprofit groups, including clubs and schools.

[18] Jack van Breen, the lead singer of the local band TinMan (which was performing an encore when the shooting began) told KPIX-TV that he heard someone shout, "Why are you doing this?"

[5] Along with the Gilroy Police Department, the San Francisco Field Division of the Bureau of Alcohol, Tobacco, Firearms and Explosives and 30 FBI agents also responded to the scene.

[15] An Instagram account was opened four days before the shooting by a Santino William Legan of the same age,[19] who self-identified as being of Italian and Iranian descent.

[34] On the day of the shooting, Legan made two posts to the account, one of which complained about the event congesting the countryside with "hordes of mestizos and Silicon Valley white twats" and instructed people to read the book Might Is Right, a pseudonymous proto-fascist manifesto.

"[5] Searches found that Legan owned both left-wing and right-wing literature,[37][30] including reading material on white supremacy and Islamic extremism.

[36] The investigation turned up evidence that Legan had been "exploring violent ideologies" and had created a list of potential targets, including the Garlic Festival as well as "religious organizations, courthouses, federal buildings and political institutions involving both the Republican and Democratic parties."

[43] Organizations, such as March for Our Lives and Moms Demand Action, and people, such as the former spokesperson for the National Rifle Association and many celebrities, also responded.

[46] In response to the shooting, in early September 2019, the San Francisco Board of Supervisors unanimously declared the National Rifle Association a domestic terrorist organization.

exists to spread pro-gun propaganda and put weapons in the hands of those who would harm and terrorize us ... Nobody has done more to fan the flames of gun violence than the N.R.A.

"[47] Mayor Sam Liccardo of nearby San Jose proposed to prevent straw purchases of firearms by requiring gun owners in the city to carry insurance.