A 33-year-old Czech woman who was climbing with her 39-year-old partner on Sunday slipped and fell - pulling him and three other people who were roped together with them. They fell about 80 metres, and then called the rescue service.
Two helicopters and eight mountain rescue experts came to their aid and flew the 39-year-old to hospital as she had serious injuries. Her companions were only slightly injured and were treated at an outpatient centre.
Police said it is believed the Czech woman lost her grip and slipped after getting snow in her crampons.
The Randkluft trail was erected in 1843 and is considered to be the oldest of its kind in the world, although it is easily reached by cable car and not particularly long.
Since 2007 it has had a continuous steel rope fixture to help climbers but it can become difficult to cross when snow melts. Only experienced climbers with glacier equipment should attempt it.