At least 84 people were killed in a shooting attack Friday on a youth camp near Oslo, police said Saturday, amid reports that a second gunman might have been involved in the shooting, DPA reported.
Police said they were investigating reports that a second man might have been involved in the shooting on Utoya island.
"We have heard the same accounts of a second gunman, and are working hard to establish if that was the case," Einar Aas of the Oslo police told the online edition of newspaper VG.
A 32-year-old Norwegian man, who has not been officially identified, was earlier charged with the shootings, as well as for a bombing in central Oslo that claimed seven lives the same day.
The 32-year-old allegedly wore a police uniform during the island shooting. However, new reports stated a second gunman was present during the shootings and was not wearing a uniform.
Oslo deputy police chief Roger Andresen termed Friday's attacks as terror acts that could be punishable with a maximum 21-year prison term.
Several media reported that the 32-year-old also had bought large amounts of fertilizer, an ingredient sometimes used in homemade bombs.
Prime Minister Jens Stoltenberg said it was "a national tragedy" and the worst act of violence in Norway since World War II.
Stoltenberg said he had been due to address the youth camp at the Utoya island, organized by the youth league of his Labour Party later Saturday. "For me, Utoya was the paradise of my youth, now it has become hell," Stoltenberg said.
Justice Minister Knut Storberget said the threat level had not changed. The premier said that was an issue to be discussed when the government meets later Saturday.
Police were searching the waters off the island and could not rule out that the death toll would rise, Andresen said.
Witnesses at Utoya told media the suspect had worn a police uniform and "deliberately targeted" people.
In an attempt to seek safety, some people jumped into the fjord. Others tried to hid in crevasses or bushes.
"I heard a shot over my head, and threw myself to the ground. Others ran in his direction and he just shot them," Ali al Hatem, 17, told public broadcaster NRK.
Andresen said the suspect had links to the far right. He has expressed extremist and anti-Islamist views on some internet sites, but had not given any specific motive that would link him to Friday's attacks.
According to the online edition of newspaper VG, the suspect a week ago set up a Twitter account citing British philosopher John Stuart Mill as saying, "One person with a belief is equal to the force of 100,000 who have only interests."
Andresen declined to comment on possible finds at the suspect's apartment in Oslo and a farm building he owned.
Norway's King Harald V said Saturday that the death of the 80 young people was an "incomprehensible tragedy."
Churches and other community buildings were opened across the country.