Updated July 25: This story was updated to reflect the subsequent retraction of the bombing claim by Helpers of Global Jihad and the arrest of the 32-year-old Norwegian man, identified as Andres Behring Breivik, a right-wing zealot who took credit for the atrocities, calling for a war against Muslims.
A group called "Helpers of Global Jihad" claimed responsibility for the bomb which ripped open buildings, including the prime minister's office, in Norway's capital, CBS News learned, and then retracted the claim.
It is apparently the same local shadowy extremist group that the Stockholm bomber in December 2010 had said he was connected to.
A Norwegian police official has said that the 32-year-old Norwegian man suspected of being behind both attacks does not appear to be linked to Islamist terrorism.
The official said the attacks probably have more in common with the 1995 attack on a U.S. federal building in Olkahoma City than the Sept. 11, 2001 attacks.
He says the suspect appears to have acted alone, and "it seems like that this is not linked to any international terrorist organizations at all."
He added that the investigation is still ongoing and that things can change.
In the 2010 Stockholm blast, the bomb, in a backpack, went off prematurely and the bomber blew himself up. However, the bomber had left behind a video protesting the Afghanistan war and the killing of Muslims.
There was no confirmation that this group was indeed responsible. When the jihadist group made its claim, investigators were trying to determine if there were links to the core al Qaeda organization. They were also looking to see if there were a connection to three al Qaeda individuals arrested in Norway July 8.
Traditionally on a Friday in Norway, government workers are allowed to leave early at 3 p.m. for the weekend -- and investigators speculate that the bomb may have been intended to inflict big casualty damage at that time.