Tornado clean-up begins as Key heads to destruction zone

The clean-up continues this morning after the violent tornado which ripped through Hobsonville yesterday afternoon.

Three people died in the storm, which also damaged about 150 houses and forced 250 residents to evacuate to the nearby Whenuapai air force base.

Civil Defence spokesman Clive Manley told Radio New Zealand this morning that building assessors would be looking at the site today to see whether residents could return to their homes.

"There's either roof damage where trees have gone through so they are secure but they will not be able to enter into them until building inspectors have deemed them safe."

Cordons remained in place.

A Fire Service spokesman said there were about six calls overnight from Hobsonville residents, most requiring assistance as more heavy rain leaked through damaged roofs.

Vector said power would likely be restored to 1300 customers later today.

Prime Minister John Key is expected to visit the site later this morning.

Auckland Mayor Len Brown said his heart goes out to all those affected.

"Some of these people will be significantly traumatised and it's just a time to embrace them and give them some care."

He said it is a disaster which has left a trail of destruction.

"Like a knife through butter for some of those trees. The powerful tornado and clearly a good size. Devastating and very, very big and old trees uprooted. Clearly a major weather event."

Auckland's Deputy Mayor Penny Hulse said people are still trying to come to grips with the death and devastation left by yesterday's tornado.

She said they have a huge job ahead.

"Everyone is reeling from the shock of the deaths and injuries and the destruction but we've had our council staff, our building inspectors out on the ground door-knocking and inspecting damage."