The boy's mother said on social media the driver drove away from the scene and didn't return until well after her son was taken to hospital.
"My big son was watching him, they were crossing the road and the driver saw them and still hit my son."
Another family member said on social media the boy was having X-rays after a hard knock to his head.
"An onlooker said the van went straight over him which is terrible to think, he's so tiny. He has tyre marks above his knees and is just so sore right now."
In another incident, ARHT assisted a 60-year-old woman who was stung by a bee in the back of her head while walking near Whangapiro on Saturday morning.
"We were told she had walked about 100 metres when she started feeling dizzy and collapsed," the spokesman said.
He said the woman was flown to North Shore Hospital in a serious condition.