At least ten people were killed on Friday as a massive bomb went off at the government headquarters in the Norwegian capital of Oslo and a man opened fire at random at a youth camp, police and media reports said.
At least seven people died when a suspected car bomb exploded near the office of Prime Minister Jens Stoltenberg. The premier is unharmed.
There were also "a lot of injuries" Assistant Chief Constable Egil Vrekke said. Police also said there were "more people dead" inside the damaged buildings. Soldiers have taken up positions in the area, which has now been cordoned off.
A short time after the bombing, a man disguised as a police officer opened fire at random at a youth Labor Party summer camp near Oslo.
State media said “several people” had been killed.
An eyewitness told the state NRK TV channel that he had seen some 20 bodies at the camp. The report has not been confirmed by police.
NRK said the shooter has now been detained. It also said witnesses described him as looking "Norwegian".
No one has yet claimed responsibility for the bombing or the shooting, the first major terrorist act in Norway. Police say the two attacks are linked.
Stoltenberg has called a crisis meeting of his government for later on Friday.
"It's hard to imagine that this is anything other than terrorism," terrorism expert Tore Bjorgo told NRK.
There are unconfirmed reports of other unexploded devices in the centre of the city and police are urging people to leave central Oslo.
Norway is a NATO member which has taken part in operations in both Libya and Afghanistan. About 400 Norwegian soldiers are serving as part of the NATO-led international force in Afghanistan.
Norway outraged many Muslims in 2006 when papers in the country published cartoons of the Prophet Mohammed.
NATO Secretary-General Anders Fogh Rasmussen called the blast a "heinous act."
Jose Manuel Barroso, president of the European Commission,spoke of his shock at the reports of the attacks in Norway, "famously associated with peace at home and peacemaking abroad."