OSLO: Anders Behring Breivik took the stand Friday to describe in detail his shooting massacre on a Norwegian island last year, in what his lawyer warned would be the most difficult testimony to hear.

On Thursday, the 33-year-old right-wing extremist had many in the Oslo district court in tears as he detailed how he set off a car bomb at the foot of a government building on July 22, killing eight people.

He also described how he had wanted to kill everybody in the building, including the entire Norwegian government.

His lawyer Geir Lippestad however warned after the end of the trial day Thursday that “tomorrow will probably be the hardest day.”Breivik told the court Thursday that he had also intended to kill all 569 people on Utoeya island when he carried out his shooting massacre the same day.

On Friday, he is set to describe in detail how he killed each of the 69 people — most of them teens — that day on the island.

As the trial day began, main judge Wenche Elizabeth Arntzen reminded survivors and family members of the victims that they were allowed to leave the courtroom if they felt they needed to do so.

Breivik, charged with “acts of terror”, has entered a plea of not guilty, saying his actions were “cruel but necessary”.