Foul weather led to the evacuation of 18 people who were practising for the annual Ten Tors challenge event.

The youngsters were airlifted from Dartmoor and taken back to the event’s base at Okehampton. 106 teams were taking part in the practice, each with six members. 40mph winds and heavy rain lashed the area.

A 14-year-old boy suffered a suspected broken ankle and another 14-year-old boy had an asthma attack. They were treated at Okehampton Community Hospital.

A helicopter from RMB Chivenor was involved in the rescue.

Last year, 14-year-old Charlotte Shaw died during practice for the event when she into the swollen Walla Brook. The event itself was abandoned because of heavy rain, and 2,400 young participants evacuated by the Army, two RAF helicopters and volunteers.

The event is organised by the 43 (Wessex) Brigade and has been open to the public since 1961. Teams walk 35-, 45- or 55-mile courses across Dartmoor over two days, this year on 10 and 11 May.