GENEVA -- Several dozen people are feared dead and around 100 injured Thursday after an explosion at a bar in the Crans-Montana ski resort in Valais Canton of southwestern Switzerland, local police said.

Those injured in the blast and subsequent fire suffered serious injuries and were taken to hospitals in Sion, capital of Valais canton, as well as in other cities, Valais Canton Police Chief Frederic Gisler said at a press conference.

An investigation is underway to determine the cause of the explosion, but authorities have ruled out an attack.

Helicopters and ambulances, including some from abroad, rushed to the scene, as the intensive care units and operating rooms of local hospitals are at full capacity, said local officials at the press conference.