A small number of people are believed to be injured and more are stranded on chairlifts after the incident, which happened around 3.25pm.
There are no details on the extent of injuries as yet, but the focus is currently on evacuating those injured and rescuing those who remain on the chairlift.
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Warmer with a mild, muggy night ahead
The headteacher of Saffie Rose Roussos's primary school has paid tribute to the little girl who was "beautiful in every sense of the word".
Ten people have died on the mountain so far this climbing season - four more than mountaineering officials expect in a typical year.