Audric, 4, was fatally hit by a car in Westmead.
Daly Thomas was clutching her son's hand when it was suddenly yanked from her grip as she crossed a Sydney road on Tuesday afternoon.
Her four-year-old son Audric disappeared beneath a grey Mazda 6 and she screamed for the driver to reverse.
She cradled her son in her lap in the middle of an intersection at Westmead but there was nothing she could do.
Next to her was her older son Austin, 6.
Paramedics tried to revive the Westmead Public School student but he died a short time later.
Many parents have expressed concern about the dangers of the intersection where Audric was killed, opposite the school.
But Ms Thomas said the road was very quiet because of school holidays.
Police said Ms Thomas and her two sons were trying to cross Mowle Street at the intersection of Hawkesbury Road when Audric was struck.
It is believed a 46-year-old woman was trying to turn onto Hawkesbury Road from Mowle Street and did not see the family walk in front of her car.
Ms Thomas said there were not many words to describe her family's loss.
“God has given him to us and God has taken him away,” Ms Thomas said.
She said she feared for her son Austin who would feel the loss of his brother the most.
“They are very alike and they are very, very close. Every time they watch TV they will sit in the same chair together. Austin is going to miss him a lot, more than us.”
Ms Thomas said her son was a very happy boy who loved to cycle in the park and dreamed of many future jobs he would do when he grew up.
“He was a very active boy and very good at school. He was very smart, he was very responsible and he was really enjoying kindergarten,” she said.
“He liked painting, mainly drawings. He would spend a lot of time with crayons and drew mostly cartoons.”
After moving from India last year, Audric had made three new friends after starting school in February.
Ms Thomas said that one day she might have the strength to meet the woman who was driving the car at the time of her son's death. But not yet.
“Of course, we pray for her too.”
Ms Thomas said she and her husband Thomas Komban Lazar had no relatives in Australia but were being supported by their friends and the Indian community.
She said she was walking home from church with her two sons and decided to cross the road because a number of cars were stopped and not moving as they waited to turn onto Hawkesbury Road.
The family said they hoped to farewell little Audric at a service at Westmead on Thursday.
Correction: A previous version of this story said many parents have expressed concern about the dangers of the intersection where Austin was killed.