Authorities in Auckland declared a state of emergency on Tuesday as flooding again hit New Zealand’s largest city.

Further north in the city of Whangarei, a student was missing after a high school group that was exploring caves got into trouble when floodwater hit.

Fire and emergency crews said they had responded to more than 200 calls, most of them in Auckland.

Many were for floodwater entering buildings, but they had also responded to landslides, falling trees and trapped cars.

New Zealand Flooding
A man attempts to clear a drain in a flooded street in central Auckland (Alex Robertson/New Zealand Herald/AP)

Severe weather has plagued North Island this year.

In January, four people were killed when floods hit Auckland, and in February, 11 people died when Cyclone Gabrielle hit.

Prime Minister Chris Hipkins said it is a difficult time for the region.

“We will get through this. We will support Auckland through it,” he told reporters.

“We know that it’s tough coming on top of everything else that they’ve been dealing with, but right now my request to people is just to keep yourself safe.”

Authorities said heavy rain was expected to continue off and on through until midnight, although they hoped the most severe downpours may have already passed.

Some train and bus services were cancelled, and authorities urged people to avoid unnecessary travel.

New Zealand Flooding
Cars drive on a flooded motorway in central Auckland (Jason Oxenham/New Zealand Herald/AP)

Police said a group of 15 students and two adults had been at the Abbey Caves in Whangarei when they got into trouble.

Search and rescue crews tried to find the missing boy, police said, while the others made it out safely.

Police suspended their search on Tuesday evening and said they would resume again Wednesday morning.

Local media reported that the missing student had been swept away by floodwater.

Whangarei Boys’ High School principal Karen Gilbert-Smith wrote on Facebook that an outdoor education class had been on a caving trip when they encountered severe weather.

She said the incident was “hugely upsetting” for all those involved.

“In time we will seek to understand how this situation occurred, but for now I ask that we stay united as a WBHS community and provide support where required,” she wrote.

Mr Hipkins said: “I do want to express my deep concern there and my absolute support for the school community.”