The search for a teen missing in a Northland cave has been suspended until Wednesday morning.
Police earlier confirmed one student was still unaccounted for inside Abbey Caves in Whangārei.
Northland District Commander Tony Hill said most of the group had made it out safely, but one student was missing.
The search was suspended at 5pm.
"This is a tragic incident and we understand many will be impacted by what has happened today," Hill said in a statement.
"Our thoughts are with the friends and family of the unaccounted for student and Family Liaison Officers and Victim Support have measures in place to look after them.
"The school is also being supported by the Ministry of Education's Traumatic Incident Team."
Hill said the students were exercising at caves but reported being in trouble at about 10.30am.
Whangārei Boys' High School earlier confirmed a group of 15 of its year 11 students were stuck in Abbey Caves, along with a teacher and an instructor.
Hill said the search is expected to resume at first light tomorrow and a cordon will remain in place overnight.
In a statement, the school Principal Karen Gilbert-Smith called the event "hugely upsetting for all concerned."
"As a school we are focusing on supporting all whānau, staff and students concerned with this event, and the wider school community, with assistance from iwi and agencies.
"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 said the school would be open Wednesday and offer support for students and staff.
Urban Search and Rescue and Police Search and Rescue are looking for the person.
"We are deeply concerned about the events at Abbey Caves today," Whangārei Mayor Vince Cocurullo said in a statement. "Our hearts go out to all those involved."
Talking to Checkpoint tonight, the mayor would not be drawn on whether it was appropriate for the school to take students to the cave today when bad weather was predicted.
"Look, that's not something that I can really comment on. At the end of the day this is something the school really needs to go through and discuss with the families."
He said the caves were not staffed.
"They are a natural wilderness area open for all to visit. To the best of our knowledge we have not had a situation like this at the caves before.
"Whenever an event like this occurs, in any environment, multiple organisations are involved in investigations. We will be taking part to identify any areas for change.
"In the meantime, our thoughts go out to everyone involved."
Northern Advocate reporter Brodie Stone told RNZ the cave the students were in had a waterfall inside it.
She said the roads on either side of the caves were flooded and prone to slips.
A man who lives beside Abbey Caves where the student was missing said the Whangārei school group should not have ventured into them in bad weather.
Ian Calder said the limestone caves were dangerous in torrential rain.
"They should not have gone in at all. I wouldn't go when it's wet like this, no way, it's too dangerous."
However, Calder said there was a safe place in the caves where someone who was trapped could wait for flash flooding to subside.
"There is quite a big open area in the middle, so if there is a flood people can get up out of the water and they can be quite safe there until the water goes down."
The caves were very popular because they were close to Whangārei and entry was free, he said.
Another Abbey Caves resident said he saw the group of students gathered about two minivans near the carpark of the area this morning.
Darron Hammond said the rainfall intensified dramatically an hour after he saw the students.
Hammond said he explored the caves in his youth and said they were "not for the faint-hearted."