A flash flood killed 6 school students and their teacher in a New Zealand national park.

The group from a school in Auckland, New Zealand's largest city, was on a hiking tour through the wilderness of the North Island's Tongariro National Park. A sudden rain storm caused the water in a river to rise to about four times its normal level and flood the area. The group was caught off guard by the torrent and swept away.

All the students were aged 16 and the teacher was 29.

The deaths of the six teenagers and their teacher were described as "an unspeakable tragedy" and every family and school's "worst nightmare" by the country’s Prime Minister Helen Clark.

Clark expressed her "profound sympathy and shock" and moved a condolence motion in Parliament.

The dead students were part of a group of 40 teenagers taking part in a weeklong canyoning course at the Sir Edmund Hillary Outdoor Pursuits Center in the small town of Turangi.
Canyoning involves navigating the gorge by swimming, clambering over rocks and hiking.

"It is a tragedy which defies belief," school principal Murray Burton said according to The Associated Press. He said the students were well equipped and were accompanied by an experienced guide, but the powerful stream left them few chances of survival.

"The amount of water that came down the canyon is particularly unusual, I've never see it rise in that short a period of time in the 24 years I've been here," said Grant Davidson, chief executive of the Sir Edmund Hillary Outdoor Pursuits Centre.

The six students - three boys and three girls - swept away were in a group of 10 and were accompanied by an instructor and a teacher.

The other four students belonging to the group and the instructor managed to survive the flood. One of the students was taken to hospital and is now under treatment.