A group of climbers spent Saturday night on a mountain ledge and were rescued by helicopter Sunday morning, after one of them was injured while rappelling the Grassi Route on the Little Sister peak near Canmore, Alta.

A Facebook post by Kananaskis Country Public Safety Section says the group reached the summit late in the day. When it started getting dark, they decided to go back down the way they came, rather than the usual descent to the Little-Middle Sister Col.

"At one point during the descent the climbers decided to use a rock horn as an anchor," the post says.

"After inspecting some pre-existing slings around the horn, the first climber rappelled down to a two-piton anchor. The second climber was on rappel when the rock horn collapsed and she began to tumble down the slope."

Hiker rescue Kananaskis

A climber is removed from Little Sister near Canmore after being injured while rappelling. (Kananaskis Country Public Safety Section)

One climber sustained injuries to her head and torso.

The climbers began a self-rescue and were able to descend to a large ledge where they spent the night.

They called for a rescue early Sunday morning after assessing their condition, and a helicopter arrived to remove them from the mountain.