The rescuers came from all around, all desperate to find the missing students who were on the final day of an adventure holiday from their Auckland school.
Some were police, some rescue experts, others were from the Sir Edmund Hillary Outdoor Pursuits Centre, or were volunteers.
The fast-flowing water of the Mangatepopo River was still about knee deep at midnight, much deeper than normal but considerably lower then when the flash flood hit in the afternoon, sweeping the group downstream, The New Zealand Herald reported.
About 20 police, civilians and outdoor pursuits centre staff were given regular briefings as they waited for their next turn in the search.
About a kilometre away, by the river, four search and rescue staff in high reflective gear and headlights took their shift scouring the river bank in poor visibility.
The students, from Elim Christian College in the Auckland suburb of Howick, were canyoning when the flash flood swept them away.
Canyoning is considered an adrenalin sport and involves scrambling, sliding or abseiling down riverbeds and waterfalls.
One of the risks of the activity is the rapidly rising water, run-off from the hills above the gorge.
In this case, it appears heavy rain on the mountain suddenly filled the gorge.
"It looks as if there has been sudden flash flooding which was difficult to foresee," Inspector Steve Mastrovich from Taumarunui police told Radio New Zealand.
"The instructor was with them and they were just caught at the wrong place at the wrong time."
The sport hit the headlines here in 1999, when New Zealanders Jon Roe and Andrew Lee, a guide, were swept to their deaths in a flash flood near the central Swiss town of Interlaken.
Conservation Department spokesman Dave Conley said the Mangatepopo Stream, which runs off Mt Ruapehu, was not traditionally used for commercial activity.
Tracks to the river were not well-known or marked. The river ran past a site the outdoor centre used, he said.
Last night's tragedy brings back memories of the 1995 Cave Creek accident on the West Coast, in which 13 students and DOC officer on an outdoor recreation course died when a platform collapsed.
A commission of inquiry found DOC had acted illegally and negligently in constructing the platform, and there had been a series of mistakes that together led to the platform collapse.
