A bystander told Newstalk ZB it looks like a truck went through the middle island of the road and smashed through a fence.
He said cars are parked up along the side of the road, including four police cars and a dog unit.
A neighbour desribed the incident.
"I was in the house talking to my mum, next thing I saw a concrete mixer come through the fence and the neighbour's fence," she said. "Heard a loud bang and that was it.
"I was lucky my son wasn't playing out at the gate.
"He [her son] would normally be out here playing, standing at the gate watching the trucks go past ... so it's lucky he wasn't here"
"He's [the driver's] saying he was trying to avoid a kid, but witnesses say there were no kids."
