Mr Ewers called the death a "complete accident" where speed was not a factor.
"The driver of the tanker, he's being looked after by the dairy company and he will need support as well. As a driver, it's the last thing you want to happen," he said.
"The family live in the vicinity and from their point of view it'll be the worst day of their life.
"Our prayers and thoughts are out with them at the moment. It's just a really sad day."
The boy's parents, who are thought to have been out of town at the time of the tragedy, are both teachers.
Relatives gathered at their house last night waiting for their return.
One relative, who did not wish to be named, said the devastating news was still sinking in.
"We're all just in such shock. He was the baby of the family," the woman said.
The driver worked for dairy company Fonterra. Its managing director of global operations, Robert Spurway, said the company was working with police and supporting the driver and local community.
"This is a terribly tragic accident and our thoughts are with the child's family and loved ones."
A Gorge Rd resident said the family of the boy were well-known and respected in the community and had lived there for at least 11 years. She said the incident was "devastating".
"Something like this, with a death, impacts hugely. It is going to affect everyone," she said.
"When I found out what happened my heart sank. I know the family, my heart breaks for them."
It's the fourth fatal road incident to hit Northland this year. On Monday, 82-year-old Aucklander Bruce Murray Stenning was killed in a quad bike crash in Kellys Bay, near Dargaville, which also injured his 62-year-old partner.
Last Saturday a 63-year-old driver died when his vehicle rolled on State Highway 1 near Waipu. And On January 12, a 45-year-old driver died when he crossed into the path of a southbound, fully laden logging truck on Smeatons Hill near Oakleigh.