Around 4:10 pm, six people were killed by the explosion of nearly 300 tonnes of expired munitions and production wastes inside the “Steingletscher” underground storage, located on the slope of the Susten pass facing Bern. The explosion, whose TNT equivalent was rated at 200 tonnes and a magnitude 3.7 on the Richter scale, caused the part of the mountainside overlooking the storage zone to slide; huge blocks of rock and pieces of the storage facility were blast over 600 m. A piece from the entrance building arch, weighting 16 t, was found 370 m away. The 11 persons preparing a pyrotechnical waste destruction campaign on the demolition ground outside the storage were not injured despite falling debris, but severely shocked. A fire in one chamber was reported 5 to 10 seconds before, thus indicating that the fire turned into a detonation within a very short time. Yet, the cause of the fire leading to the explosion remains unknown, due to the full destruction of all installations.

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