The boy had been bound around the ankles with a locked aluminum chain and had apparently escaped from his mother's apartment when passersby found him and called police.
At first the child said he had been chained as a joke, but later told rescuers that "My mom did this to me." He also told them that he was trying to hop to a friend's house who would help him out of the chain.
The boy's mother, 37-year-old Irma Jacobo Navarro, told police that he had a history of leaving home without telling her and that she could not afford a babysitter for him. According to a police spokesman, she may have been worried her son was hanging out with local gang members. NBC reported that neighbors in the apartment complex called him "rebellious" and said he'd been caught breaking windows and doors in nearby buildings.
"She basically left him in his underwear with the chain around his feet. She took the lock with her, but she left him food; she left him games to play with," Santa Ana police Cpl. Anthony Bertagna told NBC.
According to the LA Times, Navarro, who worked as a janitor, was already paying for a babysitter for her youngest child while her oldest child was at school, but could not afford a second babysitter for her 10-year-old.
Navarro was arrested for willful cruelty to a child and will probably be arraigned Monday. All three children were are in the custody of social services.