TURLOCK, Calif. (AP) — Police killed a 27-year-old man as he kicked, punched and stomped a toddler to death despite other people's attempts to stop him on a dark, country road, authorities said.

Investigators on Sunday were trying to establish the relationship between the man and the child they say he killed Saturday night. The Stanislaus County coroner said the boy appeared to be between 1 and 2 years old based on his size, according to county sheriff's deputy Royjindar Singh.

"It's been a long night of wondering, 'Why?' — not only for the officers and the passers-by who stopped and tried to help out, but for anyone. Why would somebody do this?" Singh said.

Singh said the coroner did not plan to confirm the identities of the man and victim until today.