Swiss media reports say that a letter bomb has exploded at an office belonging to the Swiss nuclear power industry in the northern city of Olten.

According to Swiss news agency SDA, two people were injured in the explosion. SDA cited local police as saying the explosion March 31 morning occurred as staff at the office of Swissnuclear were opening a letter.

Swissnuclear is a consortium of national power companies Axpo, Alpiq and BKW.