"It's been a bit of a shock."
The family had left Hawke's Bay because the father, William Town, got a job as a tanker truck driver.
Mr Town had come upon the scene of the crash by chance while driving a truck on Saturday.
"He was driving a tanker and went past the accident and suddenly realised it was his wife," Ms Smidt said.
Zane was a keen go-karter and the family regularly travelled to Palmerston North for racing events.
At the time of the crash, Mrs Town and Zane were returning to Whanganui from a race meet, with the family's youngest son Hayden, 6, as well as Mrs Town's adult daughter Rachel and her 3-year-old son Lucas.
They were recovering well, but the whole family was grieving deeply, Mrs Town's brother Michael Peck said.
Mrs Town was a wife and mother of four, and worked as an in-home child carer.
"She had three or four little children that she looked after in her home. I had the opportunity to see her with them and she was so loving with them.
"All she ever wanted to do was have children and look after children."
Zane, a Wanganui High School student, had inherited his mother's gift with children.
"It was touching to see him with his siblings and his nephew - he was very gentle and kind, he always had time for them."
Judy Redfearn, 68, of Palmerston North, who was in another car, was also killed.
The police serious crash unit is investigating and is appealing for witnesses.
The deaths of Mrs Town and Zane added to a total road toll of 10 on New Zealand roads at the weekend, which police lamented as a "preventable tragedy".
A Givealittle page has been set up to raise funds to support the Town family.
Additional reporting Wanganui Chronicle