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 and said civil servants were among the dead in Oslo.
"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 he knew some of the dead in the Oslo attack. "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.
Police say they are investigating whether the attacks were the work of one man or whether he had help.
"At Utoeya, the water is still being searched for more victims," deputy police chief Roger Andresen told reporters.
"We have no more information than... what has been found on [his] own websites, which is that it goes towards the right and that it is, so to speak, Christian fundamentalist."
'Posed as policeman'
Earlier, the number of dead from the island shooting spree, which is among the world's most deadly, was put at 10. Hundreds of young people were attending the summer camp organised by the ruling Labour Party on Utoeya island.
Eyewitnesses described how a tall, blond man dressed as a policeman opened fire indiscriminately, prompting camp attendees to jump into the water to try and escape the hail of bullets. Some of the teenagers were shot at as they tried to swim to safety.
Armed police were deployed to the island but details of the operation to capture the suspect remain unclear.
Police say they discovered many more victims after searching the area around the island. They have warned the death toll may rise further as rescue teams continue to scour the waters around the island.
The gunman is reported to have been armed with a handgun, an automatic weapon and a shotgun.
"He travelled on the ferry boat from the mainland over to that little inland island posing as a police officer, saying he was there to do research in connection with the bomb blasts," NRK journalist Ole Torp told the BBC.
"He asked people to gather round and then he started shooting, so these young people fled into the bushes and woods and some even swam off the island to get to safety."
One 15-year-old eyewitness described how she saw what she thought was a police officer open fire.
"He first shot people on the island. Afterward he started shooting people in the water," youth camp delegate Elise told Associated Press.
Mr Stoltenberg had been due to visit the camp on Saturday. Foreign Minister Jonas Gahr Store, who visited the camp on Thursday, praised those who were attending.
"The country has no finer youth than young people who go for a summer camp doing politics, doing discussions, doing training, doing football, and then they experience this absolutely horrendous act of violence," he said.
In Oslo, government officials urged people to stay at home and avoid central areas of the city.
Shards of twisted metal, rubble and glass littered the streets of central Oslo left devastated by Friday's enormous explosion.
Windows in the buildings of the government quarter were shattered and witnesses described how smoke filled the atmosphere around the blast site.
There are also concerns that more victims may still be inside buildings hit by the initial massive explosion.
Emergency services have had difficulty accessing these buildings amid concerns about further possible explosions as well as fears the blast may have left buildings unstable.
