The place of business was given as Åmot in Hedmark . On 4 May 2011 , Breivik purchased of fertilizer through Geofarm at Felleskjøpet , of ammonium nitrate and of calcium ammonium nitrate . According to neighbours , all the fertiliser was stored in his barn . After conducting a reconstruction of the bomb with equivalent amount of fertilizer on the farm in Åmot , police and bomb experts concluded that the bomb had been , about the same size as the one used in the 2002 Bali bombings . Afterwards there was significant debate in Norway about how an amateur could acquire such substantial amounts of fertiliser and manufacture and place such a lethal weapon in the middle of Regjeringskvartalet all by himself . The conclusion by Felleskjøpet was that there is no legislation to keep agricultural businesses from buying as much fertiliser as they like , and that there was nothing suspicious about Breivik 's purchase . This was confirmed by the director of the Norwegian Police Security Service , Janne Kristiansen , who stated " not even the Stasi could have prevented this attack "
2002 Bali bombings
2002 Bali bombings
2011 Norway attacks