The gunman who murdered three people at a food festival in Northern California on Sunday posted about a far-right book on Instagram moments before the attack.

Law enforcement on Monday identified Santino William Legan, 19, as the shooter who opened fire at the Gilroy Garlic Festival. Police said Legan dodged security at the festival’s entrance by cutting through a fence to gain entry. Once inside, witnesses said he sprayed gunfire on the crowd with an “assault-style rifle” before police killed him.

Authorities said Monday they were still investigating reports of a second suspect and whether Legan had ties to any group.

Shortly before the shooting around 6 p.m., Legan posted a picture from the festival on his now-deleted Instagram account reviewed by The Daily Beast. “Ayyy garlic festival time,” he wrote. “Come get wasted on overpriced shit.”

Soon after, he posted a picture with a caption that told followers to read a 19th-century, proto-fascist book. The book, which is repeatedly recommended alongside works by Hitler and other fascists on forums like 8chan, is full of anti-Semitic, sexist and white supremacist ideology. The book glorifies “Aryan” men, condemns inter-marriage between races, and defends violence based on bogus eugenicist tropes.

Ideologically motivated killers will sometimes reference manifestos before carrying out attacks, in a bid to draw attention to those works.

In his last post, Legan also complained of paved-over nature and towns “overcrowd[ed]” with “hoards of mestizos and Silicon Valley white twats.” Some fascists, particularly those who follow the hyper-egoist school of thought laid out in Legan’s recommended book, criticize industrialization and Silicon Valley lifestyles as “degenerate.”

The popular annual festival was winding down its third and final day when the first pops of gunfire were heard. Jack van Breen, a singer in the rock band TinMan, was just beginning an encore as the horrific scene broke out around 6 p.m. local time.

Van Breen told the Associated Press someone in the audience shouted: “Why are you doing this?” and the gunman replied, “Because I’m really angry.”

Witnesses say the gunman was wearing a green shirt, a handkerchief tied around his neck, and fatigues. Police said Legan legally purchased his assault-style rifle in Nevada this month. The gun was illegal to bring into California, which has stricter laws around semi-automatic weapons, the San Francisco Chronicle reported.

The Nevada gun shop that sold him the gun expressed remorse for the shooting, and questioned whether 19-year-olds should be allowed to purchase guns. "We feel so sorry for the Families of the CA shooting," the shop wrote on Facebook. "May the POS rest in Hell. Maybe people need to be 21 to buy?"

The shooting killed three people and injured more than a dozen others. One of the victims was a 6-year-old boy named Stephen Romero. “My son had his whole life to live and he was only six,” his father, Alberto Romero, told KNTV. “That’s all I can say.”

Police and SWAT arrived at Legan’s family home late Sunday night and ordered people out of the house, according to a neighbor in the residential neighborhood located about five minutes from the scene of the shooting.

Officers were seen emerging from the two-story house carrying numerous paper evidence bags and what appeared to be a camouflage rifle bag early Monday morning.