Norwegian authorities early Saturday dramatically increased the death toll in a gun attack at a youth camp on the Norwegian island of Utoya to at least 80, bringing the total number dead in a pair of apparently related attacks Friday to 87.
Police have arrested a Norwegian man for the deadly attack at the summer youth camp run by Norway's ruling party, and they believed the same man was responsible for a bombing at a government building in central Oslo several hours earlier that claimed at least seven lives.
TV2, Norway's largest broadcaster, was among media outlets that identified the suspect as Anders Behring Breivik, 32, describing him as a member of "right-wing extremist groups in eastern Norway." Despite the reports, Norwegian police would not confirm the identity of the suspect.
The 80 dead at the youth camp was a dramatic increase over a Friday police report that at least 10 had died there. Police director Oystein Maeland told reporters early Saturday in Norway that many more victims were discovered after the first toll was announced, according to The Associated Press.
"It's taken time to search the area. What we know now is that we can say that there are at least 80 killed at Utoya," Maeland said. "It goes without saying that this gives dimensions to this incident that are exceptional."
Witnesses to the camp attack said the suspect, dressed as a policeman and identifying himself as such, appeared to be doing a security check related to the Oslo bombing. They said he used the ruse to lure camp goers closer before carrying out the attack.
Video showed bodies floating in the water around the island, and witnesses said victims took to the water in an attempt to flee the carnage, but were shot anyway.
One witness told the Associated Press that campers played dead, but the gunman shot bodies in the head with a shotgun to ensure they were dead.
More than 500 people were attending the camp, and most campers were teenagers. Police indicated the death toll could continue to rise.
Oslo police spokesman Anders Frydenberg was asked by the BBC how one man was able to kill so many.
"We are having an investigation," he said. "We are hopeful the investigation will show how this is possible."
With the arrest of a lone Norwegian in the twin bomb and shooting attacks, officials have all but ruled out any connection to international terrorism.
"We have one person in custody and he will be charged in connection with what has happened," said Justice Minister Knut Storberget during a Friday evening press conference. "We know that he is Norwegian. That is what we know. I don't think it's right from my position to go into details about him."
At the same press conference, Prime Minister Jens Stoltenberg told reporters that it was "too early to say anything certain about the motive." Justice Minister Storberget said he was not aware of any threats before the two attacks.
Police said that the incidents did not appear to have international connotations, but that the borders of the country were closed.
The man in custody allegedly opened fire at the summer youth camp run by the Labour Party, the political party of both Stoltenberg and Storberget, just hours after explosions ripped through a government building holding Stoltenberg's office in the capital city of Oslo. According to media reports, the suspect had been seen in Oslo earlier in the day. Oslo is 45 minutes from the island of Utoya.
Explosives reportedly were found on the island after the assault.
Twenty ambulances and four air ambulances were dispatched to the island to pick up the wounded. Some of the campers at the island jumped into the water to attempt to swim to safety.
Stoltenberg was uninjured in the Oslo bombing. He was scheduled to visit the youth camp today.
Josh Haskell is a Carnegie Fellow.
ABC News' Miguel Marquez in Oslo, Norway, and Michael S. James contributed to this report.