A teenage boy has gone missing in a cave system amid widespread flooding in New Zealand's Auckland region.
He was among 15 students and two teachers who had gone to Abbey Caves, a series of three underground caves.
Auckland, which is New Zealand's largest city, has declared a state of emergency after heavy rainfall stranded cars, toppled trees and disrupted rail services.
Late on Tuesday, the search for the missing boy was suspended until first light on Wednesday. He was reported to be in Year 11, typically a level for students aged 15 or 16.
The Abbey Caves Reserve features limestone outcrops and sink holes. Rapidly rising water and roof falls in the caves pose significant risks for cavers, say local authorities.
It is unclear why the outdoor education class went ahead despite the bad weather, but the principal of Whangārei Boys' High School has promised an investigation, the New Zealand Herald reported.
In a statement, police Supt Tony Hill said: "Our thoughts are with the whanau (family) of the missing child, as well as all those involved in the group outing and the school."
On Tuesday, images on local media showed people rushing out of office buildings to go home early, causing traffic jams in some parts of the city.
A state of emergency was declared as a precaution and disaster response services mobilised, Auckland Deputy Mayor Desley Simpson told reporters.
She described the flooding as an "evolving emergency situation".
From January to April, the Auckland region received 90% of its average total annual rainfall, with some areas receiving up to 35mm (1.3in) of rain in just one hour.
The New Zealand Meteorological Service noted that the region is "very saturated" after a "very rough" five months.
Authorities advised people to postpone unnecessary travel and avoid driving on flooded streets.
Cyclone Gabrielle ravaged New Zealand in mid-February, leaving 11 people dead and a trail of devastation that Finance Minister Grant Robertson likened to the damage wrought by the Christchurch earthquake from 12 years ago.
New Zealand's Climate Change Minister James Shaw attributed the scale of the disaster to climate change.
The cyclone hit just weeks after torrential rains and flooding left four dead and parts of Auckland's main airport submerged.
