The little girl was their only daughter, he said.
Yesterday, the girl remained in a serious but stable condition.
It is understood her mother had just given her 20c and the child had slipped away to visit a nearby shop.
Police said the girl had pressed the button and waited until the "green man" signal showed, meaning she could cross.
The girl's school, Fruitvale, posted a message on its Facebook page, saying, "Our love goes to her family."
The girl's aunt drove past her just seconds before the youngster was hit and saw the crash in her rearview mirror, the girl's uncle said.
She saw the impact and told her husband the little girl had flown and landed hard about 30 metres from where she was hit.