Three people are missing and a dramatic rescue is underway near Back Beach in New Plymouth, where around 13 students have become trapped on Paritutu Rock.
Two students and an instructor who went in to help them remain unaccounted for.
The Taranaki community helicopter has been plucking those stranded off the rock one-by-one after the alert was raised at about 1.30.
"We are probably looking at deaths, but we are not certain," Inspector Mike Coleman told NZ Newswire.
The 2.5-metre swell was "quite rough", he said.
An inflatable rescue boat, port pilot boat and commercial fishing boat are also in the water assisting.
The Taranaki Harbourmaster says it has a boat ready to assist and ocean conditions are described as within range of a three metre swell.
Maritime New Zealand says it's compiling logistics for police around the rescue and the coastguard is also assisting.
RadioLIVE