THIS year's Ten Tors challenge will go ahead as planned, despite the tragic death of a teenager who was swept away by a swollen Dartmoor river during a practice trek last weekend. A police investigation is under way following the incident involving Charlotte Shaw, a 14-year-old student from Edgehill College in Bideford, who died in Derriford Hospital on Monday as a result of the accident. She was part of a group of ten teenagers who alerted the emergency services by mobile phone, after Charlotte was swept away in the Walla Brook, near Watern Tor. She was located by a search and rescue helicopter from RNAS Culdrose within just 20 minutes and immediately airlifted to Derriford in a very serious condition. Paul Vachon, team leader for the North Dartmoor section of the Dartmoor Rescue Group, described the weather conditions on Sunday as 'atrocious'. Mr Vachon, whose team helped during the rescue, said: 'It was sideways rain at times, the cloud base was right down, there was a blustery wind, the visibility was only about 300 metres and it was very cold.' Mr Vachon's team located the party and helped shelter them while the helicopter made two trips to take them back to Okehampton Camp. 'They were very cold and on the verge of hypothermia and obviously extremely distraught,' said Mr Vachon, who described the incident as 'very unusual'. 'The team was well prepared, had all the right equipment and had been trained well. You can be prepared for every eventuality but there's always just that one time. 'It's very unusual to have a death on the moor, especially in Ten Tors — I don't think anyone on our team can remember a situation like this happening before. 'The weather on Dartmoor is often wet and windy and cold, but the way the rivers rose so rapidly caught everyone by surprise, even the rescue teams thought it was quite unusual.' Mr Vachon extended sympathy on behalf of the rescue group to the dead girl's family. The group from Edgehill College was one of 85 teams training for Ten Tors last weekend. Two other teams also got into difficulties on Sunday and sparked further rescue operations involving Dartmoor Rescue Group and a helicopter from RAF Chivenor. Bud Francis, of the rescue group's western sector, said they were first called to help a boy from Milton Abbey School in Dorset, who had injured his knee. 'They were up the West Dart, to the east of Flat Tor. The rest of the group were beginning to suffer with severe cold as well,' said Mr Francis, whose team was then called to the other side of Flat Tor to help a team from Lipson Community College. Both groups were airlifted off the moor by the Sea King helicopter. Mr Francis said the weather at the time was very bad, though not the worst he had ever experienced on Dartmoor. 'The biggest problem is the moor can't absorb any more water and any more that's falling is immediately running off. 'What's normally a babbling brook can become a raging torrent incredibly quickly.' A police spokesman confirmed an investigation into the circumstances of the incident at Watern Tor, and the death of Charlotte Shaw was being undertaken by police. The Army, which organises the annual Ten Tors challenge, said the event would go ahead as planned in May. The Army's 43 Wessex Brigade is in charge of giving group managers training on how to prepare teams. An Army spokesman said: 'The student was part of a managed group from her college and all managers undergo mandatory training where they are instructed in training and preparing a team. 'Each team carries a comprehensive guide giving clear dos and don'ts and precautions to be taken on the moor. 'This is the first time a fatality has occurred in either training or during the event itself.'