Gilroy, July 30 -- Authorities on Monday were searching for answers to why a 19-year-old opened fire on a popular food festival less than a mile from his parents' home in California, killing two children and another man, but believe many more people would have died if officers patrolling the event had not stopped the gunman so quickly.

Santino William Legan, 19, cut through a fence and appeared to randomly target people with an "assault-type rifle" Sunday afternoon, the end of the three-day Gilroy Garlic Festival that attracts about 100,000 people to the city known as the "Garlic Capital of the World," Gilroy Police Chief Scot Smithee said.

Police responded in less than a minute, and Legan turned his "AK-47-type" gun on the officers, Sm...