At 13.26 on Friday a massive bomb explosion shook the centre of Oslo in the vicinity of government buildings. At least seven people were confirmed dead in the blast and the death toll is expected to rise as police further search damaged buildings.
The cause was found to be a car bomb created with a mixture of fertiliser and fuel; the same type use in the Oklahoma City bombing in 1995.
Speculation at the time suggested that Islamist militants were behind the blast as revenge for Norway's deployment of troops in Afghanistan as a Nato member.
But at 16.50, reports came in of shootings at a youth camp for the ruling Labour party on the island of Utøya. The gunman was described as tall, blond and Nordic-looking, and dressed in a police uniform. Before surrendering to police at around 18.27, he had killed more than 80 people and injured as many again.
The gunman was found to be Anders Behring Breivik, a 32-year-old ethnic Norwegian. Breivik has been described as a right-wing Christian fundamentalist, who had previously made internet postings criticising the government's pro-multiculturalism stance.
Breivik published a 1,500-page electronic manifesto on an anti-Islamic website detailing his beliefs and his preparation for the attacks. Large amounts of the text are said to have been copied wholesale from a similar work by 'Unabomber' Ted Kaczynski, the man behind the Oklahoma City bombing.
Breivik stated that he acted alone in both the bombing and shooting, but police are investigating claims that another gunman participated.
Questions are now being asked as to whether more could have been done in terms of intelligence, anti-terrorism procedures and technology to prevent these attacks. The Norwegian government buildings were far less well-protected than their equivalent in London or Washington DC, but they had not been subject to previous attacks or threats.
For example, a series of physical barriers and police checkpoints dubbed the 'ring of steel' was set up around key buildings in the City of London in response to the IRA bombing campaign in the early 1990s.
Norwegian police are also being questioned as to whether they could have responded to reports of the shootings quicker. There was a gap of almost three hours between the first reports of gunshots and Breivik's capture. During this time, the Norwegian police drove to the coast nearest the island, 26 miles north-west of Oslo to wait for boat transport, rather than flying across to the island in a helicopter.
Another avenue that will be explored will be the actions of intelligence agencies and their monitoring of sites, such as those Breivik posted on, for warning signs of the attacks. However, Breivik had gone to great lengths to disguise his purpose, registering a farming supplies business so he could purchase of 6t of fertiliser and not be suspected. Nonetheless, the combination of the internet postings and the fertiliser purchase could have raised an alert, perhaps through the use of computerised intelligence analysis tools.
Preventative measures have probably thwarted more planned attacks on cities than members of the public will ever know. However, as repeated attacks on the same target, such as those on London or Mumbai, have proven, determined extremists will always find a way to kill for their cause.