The boy was hit in front of his home in the 2400 block of Boykin Road about 9 p.m. by a woman driving to Hephzibah, officials say.
Tuten said the child had been in the intensive care unit at Medical College of Georgia Hospital. He died of blunt force trauma and injuries to the brain stem.
When the driver, Tuowanda Staten, 32, got out to check on the child Sunday, she was attacked by family members, according to investigators.
The boy's father, James Wright, was previously named as an attacker, but sheriff's Sgt. Blaise Dresser said Tuesday that no warrants have been issued for Wright's arrest.