Thirty runners were treated for hypothermia in blizzard conditions during a 55-mile (88km) ultramarathon in North Yorkshire.
The Hardmoors 55, in which 300 people ran over the North York Moors and Cleveland Hills on Saturday, was halted due to wintry conditions.
Cleveland Mountain Rescue Team (CMRT) helped rescue more than 80 of the competitors at Kildale from 20:00 GMT.
Several all-terrain vehicles were needed to carry out the rescue.
According to its website, the Hardmoors 55 takes runners along the Cleveland Way from Helmsley to Guisborough and contains over 2,000m (6,562 ft) of ascent.
Participants are not allowed to complete unless they are carrying certain items of kit, including waterproof jacket, survival bag and an emergency food supply.
Pete Mounsey, from CMRT, said a number of competitors had already reached the finish when organisers decided to stop the race and call for assistance.
He said 20 volunteers helped ferry runners from Kildale Village Hall to Guisborough.
"There were between 80 and 100 at Kildale who needed moving to a place of safety," he said
"It was very bad conditions when the organisers chose to end the race.
"The wind was blowing snow across and it was very cold, with the wind chill it could have been around -8C."
A spokeswoman for Yorkshire Ambulance Service said it deployed six ambulances, a rapid response vehicle, an emergency care practitioner and a clinical supervisor.
She said: "Patients were checked over at Kildale Village Hall and given foil blankets and warm drinks, but no-one needed hospital treatment."
Mr Mounsey said: "People have commented to say the race should not have gone ahead but they all managed 45 miles and it was only the last couple of hours when the weather came in on them.
"This was a well organised event and when the weather turned the organisers took the view to stop the race."