ZURICH, Aug 13 (Reuters) - A passenger train derailed into a ravine in a mountainous region of southeastern Switzerland after encountering a mudslide on the tracks, Swiss police said on Wednesday.
Several passengers were injured after at least three train carriages came off the tracks near Tiefencastel, a village less than 50 km (31 miles) northwest of the ski resort St. Moritz.
Pictures sent by passengers to Swiss media showed one train carriage had fallen into a ravine next to the tracks.
Swiss air rescue service Rega said it had two helicopters at the scene, where rescue efforts are complicated by mountainous terrain. (Reporting By Oliver Hirt and Katharina Bart. Editing by Jeremy Gaunt)