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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The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.