The five children were aged between 7 and 14, and one was sitting in the back of the station wagon with a dog and several pieces of luggage.
Mr Goodall said the child was in an "extremely vulnerable position" in the event of a crash.
After failing a breath screening test, the driver became very unco-operative and was arrested after multiple warnings for refusing to accompany the police officer.
As the passenger had also being drinking, police had to transport the entire group, including the dog, to Whangarei Police Station.
The children's father, called to pick up his children from the police station, was "pretty distraught" about what had happened.
Mr Goodall said the three elements of speed, alcohol and an unrestrained child were a recipe for disaster.
Another "classic example" of what police are trying to prevent happening on Northland's roads occurred only an hour earlier in Hikurangi.
Mr Goodall said a car driven by a 19-year-old man crashed into a tree after losing control in a 50km/h zone.
It's believed the car was travelling in excess of 100km/h.
The driver will appear in the Whangarei District Court today charged with reckless driving.
Witnesses said the car had been speeding in the street. With children playing outside and people walking it was lucky no one was hurt or killed, Mr Goodall said.