© Aimee-Jo Clark/ReutersVehicles were submerged after flash flooding in Wellington.
Some residents in Wellington, which has also been hit by landslides, have been urged to evacuate their homes.
"We encourage Wellingtonians to act quickly and not wait for official warnings if you think you need to evacuate," the city council said.
A number of streets in the city have been evacuated, and fire and rescue officials said they responded to 150 calls for help overnight.
Andrew Little, the city's mayor, said one area received a record 3in (77mm) of rain in less than an hour.
"Be very careful around floodwaters; the flooding has been strong enough to move cars, and many manhole covers have been lifted," he said in a video posted on social media.
