Norway is marking the first anniversary Sunday of twin attacks that left 77 people dead.

A number of commemorative events are scheduled across Norway as the Scandinavian nation reflects on the assaults that Prime Minister Jens Stoltenberg has described as the worst in Norway since World War Two.

On July 22, 2011, Anders Behring Breivik detonated a bomb near an Oslo government building, killing eight people. Then he went on a shooting spree at a youth camp on Utoeya Island where he killed 69 people, most of them teenagers.

Breivik, who was 32 at the time of the attacks, readily admitted responsibility for the massacre, saying he was justified because the victims had facilitated the “Islamization of Norway.”

Breivik's trial ended last month. The court is expected to issue a verdict in August.

While there is no doubt he carried out the attacks, the court must decide if Breivik should be considered criminally sane and sentenced to prison, as requested by his defense, or instead follow the prosecution's request to send him to a psychiatric ward.