At least 84 people died when a gunman opened fire at an island youth camp in Norway, hours after a deadly bombing in the capital, Oslo, police say.
Police have charged a 32-year-old Norwegian man over both attacks.
The man dressed as a police officer was arrested on tiny Utoeya island after an hour-long shooting spree. The search for other possible victims continues.
The Oslo bombing killed at least seven. Prime Minister Jens Stoltenberg said the attacks were "like a nightmare".
Mr Stoltenberg, whose offices were among those badly hit by the blast, described the attacks as a national tragedy.
"Never since the Second World War has our country been hit by a crime on this scale," he told a news conference in Oslo.
He added that he was due to have been on Utoeya - "a youth paradise turned into a hell" - a few hours after the attack took place. Many others were injured there as well as those who died.
Mr Stoltenberg said civil servants were among the dead in Oslo and he knew some of those killed. "Beyond that I cannot give further details while the police carry out their investigation."
He said it was too early too comment on a possible motive for the attacks. No group has said it carried them out.
The suspect is reported by local media to have had links with right-wing extremists. He has been named as Anders Behring Breivik. Police searched his Oslo apartment overnight.
The BBC's Richard Galpin, near the island, says that Norway has had problems with neo-Nazi groups in the past but the assumption was that such groups had been largely eliminated and did not pose a significant threat.