The 2011 Norway attacks Attack , referred Adducing to in Norway as 22 July ( ) or as 22/7 , were two sequential lone wolf domestic terrorist attacks Attack by Anders Behring Breivik against the government , the civilian population , and a Workers ' Youth League ( AUF ) summer camp , in which 77 people were killed Killing .

Breivik , dressed Wearing in a homemade police uniform and showing false identification , took a ferry to the island and opened Action fire at the participants Participation , killing Killing 69 and injuring Bodily_harm at least 110 , 55 seriously .

The 2012 Gjørv Report Statement concluded Coming_to_believe that Norway 's police could have prevented Preventing_or_letting the bombing Attack and caught Breivik faster at Utøya , and that measures to prevent further attacks Attack and `` mitigate adverse effects Influence '' should have been implemented .

The Norwegian Police arrested Arrest Anders Behring Breivik , a 32-year-old Norwegian right-wing extremist , on Utøya island and charged Judgment_communication him with both attacks Attack .

His trial took place Process_start between 16 April and 22 June 2012 in Oslo District Court , where Breivik admitted Telling carrying out Action the attacks Attack , but denied Justifying criminal guilt and claimed Statement the defense Defending of necessity ( ) .

On 24 August , Breivik was convicted as charged Judgment_communication and sentenced Rewards_and_punishments to 21 years of preventive detention in prison Prison , the maximum sentence Rewards_and_punishments allowed in Norway .