Two individuals passed on and 21 were injured from the get-go Saturday in what police calls an "demonstration of Islamist psychological warfare".
The shootings were in and close to the London Pub, a famous LGBTQ+ scene, the Herr Nilsen jazz club and another bar.
Norway's state head told the BBC the suspect was addressed in May, yet was not considered a danger at that point.
"We presently need to see the consequence of an examination," PM Jonas Gahr Stoere told the BBC's Newshour program late on Saturday.
The shooting began at around 01:15 nearby time on Saturday (23:15 GMT Friday), authorities said.
Observers said the suspect took out a firearm from his sack and began terminating, driving frightened individuals to either hurl themselves to the ground or escape.
The assailant was captured by cops - who were helped by observers - minutes after the fact. Two weapons were recovered at the crime location by police, one of them a completely programmed firearm.
The specialists later said the suspect was a Norwegian public.
Of the 21 harmed, 10 were in a difficult condition.
The fear ready level in Norway has now been raised to its most elevated level, however the country's PST knowledge administration said it presently had "no sign" further goes after were logical.
Oslo's yearly gay Pride march was because of be hung on Saturday, and was officially dropped on police exhortation.
However, notwithstanding that, many individuals walked close to the scene later in the day, yelling: "We're here, we're strange, we will not vanish!"
"I believe it's fabulous that this walk is occurring, any other way he would have won," one lady in her 50s told AFP news organization.
Rainbow banners and blossoms were laid close to the location of the assault, which was fixed off by police tape, and onlookers helped each other with embraces.
The shooter was referred to security administrations starting around 2015 as a "thought radicalized Islamist", and had a background marked by dysfunctional behavior, Norway's PST insight administration said.
"There is motivation to imagine that this might be a disdain wrongdoing," police said prior. "We are exploring whether... Pride was an objective in itself or whether there are different thought processes."
Lord Harald, Norway's ruler, said he and his family were "appalled" by the brutality. He said "we should stand together" to guard "opportunity, variety and regard for one another".
EU Commission President Ursula von der Leyen tweeted that she was "stunned by the intolerable assault on blameless individuals", while French President Emmanuel Macron said: "We stand more grounded against disdain assuming we stand together."
In the US, John Kirby, a representative for the White House's National Security Council, said: "All of us are frightened by the mass shooting in Oslo today focusing on the LGBTQI+ people group there and our hearts clearly go out to the every one of the groups of the people in question, individuals of Norway, which is an enormous partner, and obviously the LGBTQI+ people group there and all over the planet,"

Witnesses who were at the London Pub have told how they fled to the basement, where 80 to 100 terrified partygoers were trying to hide.
Bili Blum-Jansen told TV2: "Many called their partners and family, it felt almost as if they were saying goodbye. Others helped calm down those who were extremely terrified."
Another survivor told how he was hit by flying glass.
"I just noticed that a shot was fired, and I was hit by a shard of glass. There were more and more and more shots, so I escaped into the inner bar and tried to get as many as possible with me," he told Norway's public broadcaster NRK.

"I saw a man show up with a pack, he got a firearm and begun to fire," said columnist Olav Roenneberg of public telecaster NRK, who was nearby at that point.
A lady told the Verdens Gang paper that the shooter had trained in on his objectives. "At the point when I comprehended that it was significant, I ran. There was a man shrouded in blood unmoving on the floor," she said.
Another man told the paper he had seen a many individuals on the ground with head wounds.
In the end, I would just like to say, Islam is a peaceful religion and it doesn't allow to threaten any innocent life.
Thank you for reading my article
You must be logged in to post a comment.