Another resident on the north-east Adelaide street said the mother used to walk the little girl up and down the street.
"I used to see the little girl, she was so cute," she said. "I feel so sorry and sad, it's terrible. I feel sorry for the little girl and her parents."
Inspector Jerome Teakle said the accident was tough for the family and emergency service officers who were at the scene.
"It's terrible," he said. "(I) just can't stress enough, just to remind all parents to take care and know where your children are."