Six of the dead were teenagers from an Auckland college and the seventh was a teacher. They had been part of a larger group when an unexpected wall of water swept through a gorge on Tuesday afternoon. Earlier reports had said five people had been killed.

'It looks as if there has been sudden flash flooding which was difficult to foresee,' Police Inspector Steve Mastrovich told Radio New Zealand. 'The instructor was with them and they were just caught at the wrong place at the wrong time.'

The students had been canyoning in the rugged and isolated Mangetepopo Gorge near the Tongariro National Park in the central North Island.

They had been wearing wetsuits, lifejackets and helmets and were led by an experienced instructor.

The students had been attending a leadership course at the Sir Edmund Hillary Outdoor Pursuits Centre.

The director of the centre said there had been no warning of the heavy rain and when the students entered the gorge the river was at a low level.

'I am comfortable this was a normal activity we had with this age group in these sort of conditions. Obviously if we had known or predicted about the pulse of water we would not have been there,' Grant Davidson told TV3. -- REUTERS