A Fire and Emergency NZ spokesman said fire crews were called to the scene by the Automobile Association at 1pm.
"We went and assisted with the child trapped in the vehicle," the spokesman said.
He did not have information about whether the child required medical treatment.
An Automobile Association spokeswoman said the fire service "smashed a window and removed the child from the vehicle".
Maloney said he first noticed something was up when he saw the fire truck parked on the side of the road, facing oncoming traffic.
As he went past, he saw a small SUV with the rear window on the driver's side smashed in.
There was no other car around or sign of an accident.
Then he saw the girl being assisted by a fireman and older lady.
The older lady was holding an umbrella above the girl.
"To my quick view driving past, the girl looked soaked," Maloney said.
He said he had two young kids going to a nearby school and the incident was a reminder to parents to take care of their young ones during the upcoming summer.
The AA spokeswoman said the service attends hundreds of callouts every year for children and pets trapped in vehicles.
"It's a particular issue during the hot summer months when the internal temperature of cars can rise very quickly, even if the windows are cracked or the car is parked in the shade," she said.
"We strongly advocate for people to never leave their children or pets in vehicles."
Anyone who sees a child or pet distressed in a locked car can call 0800 500 222.
AA will send out a team to the scene and notify emergency services.
"The caller doesn't need to be an AA Member, nor will they be charged if they require emergency lockout assistance," she said.
