A landslide buried the Calanca road between the municipalities of Buseno and Rossa in canton Graubünden on Friday evening, RSI reported.
Around 300 cubic metres of debris broke loose after heavy rainfall and now the valley is cut off from the outside world. Around 350 people are isolated, but no one was injured.
The rocks are estimated to have fallen onto the road from a height of about 200 metres at around 11 pm on Friday evening, Sven Fehler of the cantonal civil engineering office told the Keystone-SDA news agency.
After authorities flew over the air and inspected it, experts did not expect any further demolitions. Therefore, the clean-up work could already begin. However, the road in the Calanca Valley will be closed at least until Sunday evening.
As soon as the debris is removed from the road, it will be repaired and if everything goes according to plan, the authorities will be able to reopen the Calanca road on Sunday evening at the earliest.
A further assessment of the situation followed on Sunday morning. The demolition site and especially the rock next to it will then be monitored with radar, Fehler added.