Officer Julie Sohn said Monday the child abuse unit is investigating because of the boy's age.
The Los Angeles Times, citing unnamed people familiar with the case, says the parents of Lucas Anthony Tang of Garden Grove had been searching for him when they learned he had fallen Sunday night.
It's unclear how the boy plunged over the low wall that fronts the luxury box. The official cause of death is awaiting further investigation.
A Los Angeles TV station reported that the boy was taking pictures when he fell, but said on Monday that information couldn't be confirmed.