When the van arrived the resident said she had moved all the kids off the street on to her property, including the two-year-old.
She said the boy had "darted out" on to the street chasing a neighbour's dog.
"It was over in two seconds ... I was right there, but I was half a second too late."
The cul-de-sac was a popular area for kids from Bristol Place and the surrounding area, and it had been busier than usual because of school holidays.
Another neighbour had put her son in the van and gone back into her home.
She went on to the street after she "heard yelling". "It was so scary, I had my kids out there."
Acting traffic Sergeant Nic Renall said police were unsure how it had happened.
They were not sure of the sequence of events but the van had been "caught up with" and the driver was interviewed by police yesterday afternoon.
Mr Renall said it was not a hit and run. He said he thought the boy had been playing in the cul-de-sac, which was quite common for the kids in the street to do.
The boy was taken to a local doctor but he was immediately sent to hospital from there.
Jo Harris, the area manager for The Learning Adventure's parent company, Evolve Education Group, said the company was undertaking a review process and had contacted the Ministry of Education and victim support.
"First and foremost our thoughts are with the boy and his family."
Ms Harris said she could not confirm whether the youngster attended the centre.
