Residents of Gilroy, California held a candlelight vigil on Monday after a teenager shot visitors attending a popular food festival over the weekend. /VCG Photo

Three people, including a six-year-old boy and a 13-year-old girl, were killed in the incident. /VCG Photo

Santino William Legan, 19, cut through a fence at the Gilroy Garlic Festival last Sunday and shot people, seemingly at random, with an assault-style rifle, according to local police. /VCG Photo

California police and FBI agents were still trying to determine the shooter's motive and further investigate the case. /VCG Photo