Two people were killed and at least 21 wounded in a shooting in central Oslo early on Saturday that police are treating as a terrorist attack.
Police said a Norwegian man of Iranian descent had been arrested following the attack, which occurred at around 1am in three locations close together in the centre of the Norwegian capital.
"The police are investigating the events as a terrorist attack," police said.
The suspect was known to domestic intelligence services and had had brushes with the law for minor infractions, such as knife and drug possession, police said, without naming him.
They said they had seized two firearms: a handgun and an automatic weapon.
Police received the first reports at 1.14am and the suspect was arrested five minutes later, police official Tore Barstad told a press briefing.
"Everything indicates that there was only one person who committed this act," Mr Barstad said.
The shootings took place outside the London Pub hours before Oslo’s Pride parade was due to take place. Organisers cancelled all events planned for Saturday on the advice of police.
Police said 10 of the wounded had suffered serious injuries.
Witness describes terrifying scenes at Oslo shooting
"He looked very determined about where he was aiming. When I realised it was serious, I ran. There was a bleeding man lying on the ground," a woman who saw the incident told the Verdens Gang newspaper.
Another witness quoted by the paper mentioned the use of an automatic weapon — which the police did not confirm — and described it as "a war zone".
"There were a lot of injured people on the ground who had head injuries," he said.
Olav Roenneberg, a journalist from Norwegian public broadcaster NRK, said he witnessed the shooting.
“I saw a man arrive at the site with a bag. He picked up a weapon and started shooting,” Roenneberg told NRK. “First I thought it was an air gun. Then the glass of the bar next door was shattered and I understood I had to run for cover.”
Generally peaceful, Norway was the scene of bloody attacks on July 22, 2011, when right-wing extremist Anders Behring Breivik killed 77 people.
He first detonated a bomb near the government headquarters in Oslo, killing eight people.
He then disguised himself as a policeman and went on a shooting spree at a summer camp for left-wing youth on the island of Utoya, killing another 69 people — most of them teenagers.
With reporting from agencies.
