Several people have been injured after a train came off the tracks near the Swiss village of Tiefencastel, around 30 miles from the ski resort of St Moritz.
The Swiss air rescue service Rega said it had two helicopters at the scene.
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Northern and eastern areas will see a touch of frost at first, but most places will see sunshine.
The prince will meet the country's indigenous people on the penultimate day of his tour of the West Indies.
The University of Colorado said it is also terminating Dr Michelle Herren's non-paid medical faculty appointment.