3 people have been killed by a rare tornado in New Zealand.

It hit western suburbs of the city of Auckland on Thursday afternoon forcing hundreds to evacuate their homes.

The Reuters news agency reports that the tornado, driven by a powerful storm cell, tore concrete slabs from a building site and dropped them onto a truck killing 2 people inside.

"The sky went black"

"I saw it coming across the river, the air went very electric and the sky went black. And then the wind started to whistle. This was like a juggernaut roaring through here" witness Suzanne McFadden told Newstalk ZB radio in  New Zealand.

Military personnel are going from door-to-door to check if more people are trapped and authorities warned of more severe weather to come later.

The New Zealand Herald newspaper says rescue teams are searching a school site for workers thought to be trapped beneath fallen concrete blocks in the west Auckland suburb of Hobsonville.   Details on the 3rd death are not immediately available, but it's understood at least 7 people injured in the storm were sent to hospital.

New Zealand has been hit by several natural disasters in recent years including a magnitude 6.3 earthquake that struck the southern city of Christchurch in 2011, killing 185 people.

Another tornado in Auckland last May killed one person.