The landslide happened after heavy rain in eastern Switzerland overnight. Police spokesman Peter Faerber said some people had been slightly wounded, but could not immediately confirm the exact number of injured.
The accident occurred on a mountainous train line near Tiefencastel, between Chur and St Moritz in the region of Graubuenden.
The Swiss rail system is widely seen as among the safest in the world. But Wednesday's accident comes two days after three people died when their minibus was hit by a train in central Switzerland.