First, a powerful explosion rocked central Oslo Friday afternoon, shattering government buildings including the office of Norwegian prime minister Jens Stoltenberg, who was unharmed.
Less than two hours later, a second attack, by a sniper, unfolded on the island of Utoya, some 20 miles from Oslo.
In the second attack, a gunman dressed in a police uniform opened fire on a Labour party youth conference on the island of Utoya, attended by 600 people, that the prime minister had been due to attend.
85 people have been killed in the Utoya shootings, many of them teenagers, Norwegian police said Saturday. Seven people have been killed in the Oslo blast. Four people are still missing after the Utoya shootings. Several other people have been hospitalized with injuries from both attacks, and authorities warned the death toll could rise.
Authorities on Saturday formally charged a 32-year-old Norwegian man, identified as Anders Behring Breivik, as responsible for both attacks. He was taken into custody Friday on the island of Utoya.
Norwegian Prime Minister Jens Stoltenberg, in a press conference Saturday, called the killings a national tragedy. It is the worst violence Norway has experienced since the war, he said.
Police said they did not yet know the motive for the attacks, but Breivik has expressed far-right wing and anti-Islamic views on his Facebook site and Internet postings. Breivik purported to run an agricultural concern, Geofarm, since 2009; but some reports Saturday suggested that may have been a cover through which he purchased 6 tons of fertilizer in May to be used as explosives. Norway's VG newspaper reported that Breivik had only in April changed the address of his firm, Geofarm, from his Oslo apartment to the farm where he assembled the massive bomb used in the terrorist attack Saturday. He also owned several firearms, reports said.
In a January 2010 Internet posting, Breivik expressed antipathy to traditional political parties for not rejecting Islam and multiculturalism. Breivik expressed admiration for far-right, anti-Islamic parties, such as Geert Wilders "Freedom" party in the Netherlands and Norway's so-called Progress party, of which he had been a member.
"Tories in the UK, in line with the Conservative Party in Norway, is about to be made completely culturally irrelevant to 'real' cultural conservative parties such as the Progress Party, Geert Wilders' Freedom Party, etc. who can rightly call himself a true conservative (cultural conservatives)," Breivik wrote. "These 'traditional conservatives' refuse to recognize these new options and call them populists. Meanwhile, they are increasingly aware that they will continue their journey towards irrelevance valley as long as they do not take a stand against multiculturalism wonderful doctrines."
He wrote just one post to Twitter last Sunday, under his Twitter handle, @AndersBBreivik: "One person with a belief is equal to the force of 100,000 who have only interests."
The terrorist attack "is more Norway's 'Oklahoma City' than 'World Trade Center,'' police officials told the Associated Press.
Reports said Breivik, dressed in a police uniform and saying he was coming to the island in response to the Oslo bombing, opened fire with an assault weapon on hundreds of young people gathered on Utoya for a Labour Party youth conference. The massacre went on for as long as two hours, reports said, saying it took police more than 90 minutes to arrive on the scene, when he surrendered.
"He first shot people on the island," one camper, Elise, 15, told the Associated Press. "Afterward he started shooting people in the water."
Police also said that undetonated explosives had been found on the island, apparently of the type used in the Oslo bomb blast.
The massive explosion "blew out most windows on the 17-story building housing [Prime Minister Jens] Stoltenberg's office, as well as nearby ministries including the oil ministry, which was on fire," Reuters reported.
The Oslo bomb went off at approximately 3:30 pm local time, and the Utoya shootings began at about 5:20 pm, Norwegian financial journalist who writes under the handle @Finansakrobat posted to Twitter.
Norwegians appeared deeply shocked by the violence, which has been rare in their country.
Norway has relatively light security because it has experienced very little domestic or international terrorism before, said Jim Arkedis, a former Defense Department counter-terrorism analyst. "If you combine opportunity with, relatively speaking, lax security of Oslo, it does not have the level of security of a London or Madrid," he said.
Stoltenberg, speaking at a press conference late Friday to a shaken nation, urged solidarity.
Tonight, we will comfort each other, he said."Tomorrow, we shall show the world how strong Norwegian democracy really is."