Police and the lawyer for the Norwegian man who confessed to Friday's bombing in Oslo and a shooting rampage at a youth camp, said Sunday that he claimed to have acted alone, despite the statements of some witnesses who said there was a second gunman.

Authorities said Anders Behring Breivik confessed to the twin attacks, but denied criminal responsibility, saying his actions, which killed 92 people, were “atrocious” but necessary.

Acting Oslo police chief Sveinung Sponheim told a news conference Sunday that there are no other suspects in the attacks, but authorities would investigate everything that Breivik said.

Breivik has been charged with terrorism and will be arraigned Monday.

Defense lawyer Geir Lippestad said Saturday that Breivik has expressed willingness to explain himself in court.

Breivik was arrested for allegedly shooting at least 85 people dead at a youth camp on idyllic Utoeya island, sponsored by the country's ruling Labor Party, and killing seven more in a car bomb explosion that ripped through government buildings in the Norwegian capital, Oslo.

Police describe the 32-year-old as a “fundamentalist Christian” with political views that leaned to the right. Police say he had posted anti-Muslim rhetoric online, and news accounts said he has been a strong opponent of multi-culturalism in Norway. Norwegian media say he wrote a 1,500-page manifesto before the attack.

Earlier Saturday, a farm cooperative said it sold six tons of fertilizer, a product sometimes used in bomb-making, to Breivik in May.

Breivik managed an organic farm called Breivik GeoFarm, growing vegetables, melons, roots and tubers. The cooperative described the size of his fertilizer purchase as a “relatively standard order” for a farm like his but alerted authorities about the sale when it learned he was a suspect in the bombing. Norwegian media say the massive bomb that exploded at the government building was made from fertilizer.

Norway reeled with horror at the twin attacks. Prime Minister Jens Stoltenberg called the assaults – the worst in Norway since World War Two – “a national tragedy…a nightmare.” He called the bombing and shootings “bloody and cowardly attacks” and said Utoeya has been turned from “a paradise into hell.”