The attack was reported just before 3 p.m. in the San Bernardino County community.
Investigators say the boy was home with a family member when he was attacked by the family dog, a pit bull.
It is not immediately clear why the dog attacked.
The family member called 911 but paramedics were unable to save the boy's life.
The dog was taken into custody by Animal Control.
Detectives from the San Bernardino County Sheriff's Department Victor Valley station are on scene and interviewing the family.