A gunman killed at least 80 people at a youth camp of Norway's governing Labor Party on Friday, just hours after a bomb ripped through the central government district in Oslo, killing seven.
Norwegian police have detained a 32-year-old Norwegian man, named by local media as Anders Behring Breivik, in connection with both attacks. There were reports of his links with right-wing extremism
WILL MCCANTS, FORMER U.S. STATE DEPT ADVISER ON COUNTERING VIOLENT EXTREMISM
"We've never seen anything like this. A right-wing extremist bombs the nerve-center of his home nation and then massacres dozens of his fellow citizens miles away."
"I will be shocked it he pulled it off alone. But if he did, it not only raises concerns about the rise of right-wing violence in Europe but also the rise of the super-empowered lone wolf."
JAKUB GODZIMIRSKI, SENIOR RESEARCH FELLOW AT NORWEGIAN INSTITUTE OF INTERNATIONAL AFFAIRS
Godzimirski said the attacks were more likely the work of a right-winger than Islamist militants.
"It would be very odd for Islamists to have a local political angle. The attack on the Labor youth meeting suggests it's something else. If Islamists wanted to attack, they could have set off a bomb in a nearby shopping mall rather than a remote island.
"This attack has more in common with the Oklahoma City bombing than an Islamist attack."
JONATHAN PARIS, INTERNATIONAL Center FOR THE STUDY OF RADICALISATION, KING'S COLLEGE LONDON
"We do know that al Qaeda would have a motive to do this...but beyond that we don't have any evidence at this time that there's a definite link to al Qaeda," he told Britain's Sky News. But the attacks could also be the work of "homegrown right-wing zealots."
SAJJAN GOHEL, ASIA-PACIFIC FOUNDATION
"What was the ideological motivation, was it local or trans-national? Norwegian nationals have traveled abroad for terrorist training and in the past there have been linkages to Iraq, the Central Asian republics and Xinjiang in China.
"An attack in Norway followed by failed plots in Sweden in December 2010 and against the (Danish) Jyllands-Posten newspaper highlight that Scandinavian countries are in the firing line for terrorist activities. It seems no longer a factor that countries like Norway and Sweden are immune from terrorism because of their neutral foreign policies."
(Reporting by William Maclean and Wojciech Moskwa, Editing by Matthew Jones)