SAN FRANCISCO, July 29 -- A six-year-old boy and a 13-year-old girl were among the victims killed in a shooting at an annual garlic festival held in Gilroy city, Northern California, Gilroy Police Chief Scot Smithee said Monday.

Smithee told a press conference the deaths also included a male in his 20s and the shooter, who was gunned down within "less than a minute" after police officers engaged and fatally wounded the suspect who was identified as 19-year-old Santino William Legan.

He said the investigators found the weapon that suspect used was "an SKS AK-47 type assault rifle," which was purchased legally in the state of Nevada on July 9.

The police chief updated the number of total injuries to 12 who survived the shooting at the annual Gilroy Garlic Festival. The injuries were previously put at 15 on Sunday.

He thanked the first respondent police officers for engaging the suspect rapidly to prevent more possible casualties. "It could have gone so much worse, so fast," he said.

Craig Fair, deputy special agent in charge of the San Francisco Division of the Federal Bureau of Investigation (FBI), said FBI agents were assisting in the probe of the festival shooting that occurred late Sunday to find out what was behind the attack.

"Our...principal concern at this point is motivation and ideological leanings," he said.

On Monday, Amy Storey, president of Keuka College in New York, confirmed in a statement that Trevor Irby, a biology major who graduated from the college in 2017, was the third victim of the mass shooting at the garlic festival over the weekend in California.

The Gilroy Garlic Festival, which started in 1979, is now known across the globe as the world's greatest summer food fair, featuring three full days of garlicky food, live entertainment, and family fun.

Sunday was the last day of the annual three-day festival, which often attracts tens of thousands of garlic lovers.