Beginning in the suburb of Albany around 3 p.m., it left a trail of destruction and debris from Birkenhead through to Point Chevalier.
Albany's Mega Centre was right in the path of the tornado which left many buildings severely damaged.
Shortly after the tornado struck, Lucy Zee posted on Twitter: "Albany mall has been evacuated. I'm shaking so bad. Roof collapsed. I thought I was gonna die," according to One News.
Witnesses reported cars with people inside being tossed up in the air and trees being pulled out of the ground.
WeatherWatch Analyst Philip Duncan said that the tornado reached speeds of around 200 km per hour.
“They tend to form and land in places where no-one lives for example the west coast of the South Island or across farmland in Taranaki.”
The weather office had predicted thunderstorms and flash flooding. The tornado came as a shock, Mr Duncan told NewstalkZB, particularly one of that strength.
He said the front system was heading toward the Coromandel/Bay of Plenty area, with a risk of further tornadoes of lesser strength.
