Three people were killed and at least seven injured, some critically, when a storm described as a mini tornado swept through western suburbs of New Zealand's biggest city, Auckland, on Thursday. Police said 150 houses were damaged in the suburb of Whenuapai, leaving many uninhabitable, and 250 residents were evacuated to a nearby air force base. Authorities declared a no-go area and a one-square-kilometre residential area was cordoned off by troops, dpa reported. Two people died when a slab of concrete fell onto a truck at a school construction site and the third was killed by a falling tree, news reports said. The storm, featuring 110 kilometre-per-hour wind gusts and twister funnel clouds, ripped off roofs, blew out windows, tore down power lines and uprooted trees in torrential rain. Flights in and out of Auckland International Airport were cancelled because lightning strikes stopped aircraft refuelling and thousands of passengers were reported stranded. A stretch of suburban motorway was closed after being covered with debris from trees and collapsed anti-noise walls. Police warned of extensive flooding and urged people to stay off the roads unless it was necessary to travel.