Forty thousand people are still without power in the Auckland region after a powerful storm left a trail of destruction across the upper North Island.
One child was taken to hospital with minor injuries after a tree smashed through a roof in Manly, Whangaparaoa, about 1.10am.
In Blenheim a 12-year-old girl was swept away by floodwaters on her way to school, saved only by the quick thinking of two passers-by.
Emergency services in Auckland city attended more than 600 calls after midnight, as the city's streets were littered with debris.
Girl swept away in Blenheim
A 12-year-old girl swept away by a flooded Blenheim river while walking to school this morning was saved by two quick-thinking passers-by.
Police say a tragedy was averted when a 17-year-old man and another man leapt to the girl's aid.
The girl was swept away by a raging Taylor River, near High St, at about 8.45am.
The two men chased her along the river bank and eventually recovered her from the water near Beaver Rd, police said.
The 12-year-old girl has been taken to hospital in a serious condition.
The teenage rescuer has also been taken to hospital suffering mild hypothermia. The other man did not require medical attention.
Senior Sergeant Dan Mattison said the quick actions of the teenage boy and the other man involved in the rescue had saved the girl's life.
Power still out to tens of thousands
Vector crews have worked throughout the night to attend to numerous faults after two huge wind blasts up to 145km/h swept through the city, one at 11pm last night and another at 1am.
Storm damage on Princes St, Auckland CBD pic.twitter.com/UvbbFNVgT6
— 95bFM News (@95bFMNews) June 10, 2014
Forty thousand customers are still without power in the Auckland region, Vector says.
Most power has now been restored to the 6000 outages in Auckland south of the Harbour Bridge.
In the northern region up to Warkworth, a further 15,000 have been restored, with 40,000 still without power.
Vector spokeswoman Sandy Hodge said 30 crews were working on the northern network, along with seven Treescape crews.
"If you are medically dependent and are without power, then please contact a family member or friend who has power, or if none of these options are available please go to your nearest hospital."
One of the Vector crews had a lucky escape when a large tree came down next to their truck, trapping the vehicle.
Power was out too to areas in the Coromandel and south Waikato.
Powerco Acting Electricity Operations Manager Phil Marsh said the first of the power cuts occurred around midnight.
"Field crews are working to restore supply as quickly and safely as possible," Mr Marsh said.He warned that power lines on the ground must be treated as live at all times.
"Stay away from any downed power lines and call Powerco's emergency number 0800 272727."
Whangaparaoa resident Dennis Hawnt was woken last night to find a large tree had crashed through his garage and sleepout.
Mr Hawnt said he woke just after midnight and found that power in his Arkles Bay home was off.
"I went outside and saw the tree had fallen on the garage and the sleepout, but it was good because nobody was in the building at the time."
A local fire brigade was in the area, and came to assess the damage.
"It's quite lucky that it didn't land in a more inconvenient place, like on one of the cars or on the house."
Mr Hawnt said he would seek advice from his insurance company before embarking on the "big job" to remove the tree.
Motorways affected, Harbour Bridge closed
The northwestern motorway off-ramp at Great North Rd, which was closed earlier because of fallen trees, is now open.
One tree was blown onto the road by high winds last night and just as contractors had cleared it, a second tree was blown down.
The Auckland Harbour Bridge had to be closed for a time after wind gusts made the structure move.
NZTA's Ewart Barnsley says lanes one and two southbound were closed early this morning because of the trailer of a Toll Transport truck that rolled just before 3am. It was blocking the clip-on.
"Even though it seems that the worst of the storm may have passed, we're just asking drivers to take extreme care.
"Driving's going to be a bit of a challenge getting into work this morning."
Ewart Barnsley says that means keeping a good following distance, lights on, and speed down.
Canterbury bears brunt of flooding
In some of the worst flooding yesterday, emergency services helped evacuate 21 elderly dementia patients from a flooded North Canterbury rest home.
The residents spent last night in an emergency welfare centre after a torrential downpour caused a stream behind Bainlea House to breach its banks.
Civil Defence response teams pumped water from houses in the area. Residents waded through flooded streets in an attempt to unblock drains, while children played on inflatable dinghies.
Flooding closed the Rangiahua bridge on State Highway One at Horeke in Northland last night.
State Highway 10 near Kaeo in Northland was also affected by flooding and restricted to one lane.
NZ Transport Agency regional journey manager Jacqui Hori-Hoult said winds had brought down trees in Northland and rain had caused flooding.
"With night falling so quickly at this time of year, it is a case of expecting the unexpected particularly in rural areas with little street lighting.
"People should drop speeds and increase following distances to reduce the risk of a crash if a vehicle ahead has to brake suddenly."
MetService forecaster Leigh Matheson said Northland and Auckland residents would not get any respite from the weather until this morning.
"All through that region there will be significant gales ... it could be hazardous for eastern areas of Auckland," she said.
"[This] morning everything should be much quieter. The rains should have eased right off and the winds dropped right out."
MetService says the front will then probably move from Auckland and Northland, and onto Gisborne and Hawkes Bay for the next two days. Ms Matheson said the western Bay of Plenty could get up to 200mm of rain in 48 hours.
In Canterbury, the worst would have passed by today.
"The sun may turn up on Friday. It's a pretty wet week, is the general theme."
- Additional reporting Newstalk ZB
