Norway’s security service has raised its terror alert to the highest level, saying it believes the suspect arrested after two people were killed in overnight shootings in Oslo is a radicalised Islamist with a history of mental illness. Norway’s PST intelligence service said on Saturday that the 42-year-old Norwegian national of Iranian origin had been known to security services since 2015. Roger Berg, the acting PST chief, told a news conference the terror alert was being raised from “moderate” to “extraordinary”. He said the attacks were “an extreme Islamist terror act” and that there was “an unresolved terrorist situation”. He said intelligence services had spoken to the suspect last month. They did not consider him to have violent intentions but were aware that he had “difficulties with his mental health”. The consecutive shootings in three locations in central Oslo, including a gay bar, came hours before the start of Norway’s Pride celebrations, which were called off – though several thousand people walked the route of the capital’s parade in solidarity. “Obviously the atmosphere has been marked by this tragedy,” one marcher, Håve Fjell, told the public broadcaster NRK. “But it’s good to see so many defying fear and standing up against hatred and prejudice.” Cancelling the parade was the wrong decision, he said: “That just gives a bigger victory to the perpetrator.” Norwegian media reported that the suspect was of Iranian Kurdish origin and had arrived in Norway as a child. Berg said the suspect, who had “a long history of violence and threats”, had been on the PST’s radar “in connection with concerns about his radicalisation” and membership “in an Islamist extremist network”. The PST has previously characterised attacks by suspects with known mental health problems as “acts of terror”, such as that carried out last year with a bow-and-arrows and other weapons in Kongsberg, outside Oslo in which five people were killed. The suspect in those killings, Espen Andersen Bråthen, had once briefly been flagged for radicalisation but was transferred after the attack to the public health service amid concerns over his mental health and doubts he could be held legally responsible. A senior police lawyer, Christian Hatlo, told a news conference earlier on Saturday that 10 people had been seriously injured in the shootings and 11 more were slightly wounded. Two weapons, a pistol and an automatic rifle, had been seized, he said. The alleged gunman was suspected of “murder, attempted murder and terrorist acts”, public broadcaster NRK reported the prosecutor as saying. “There is reason to think that this concerns a hate crime. That is one of the hypotheses.” Police said they were investigating “whether Pride was a target in itself, or there were other motives”. Officials’ initial assessment was that “there are grounds to believe he wanted to cause grave fear in the population”, Hatlo said. The Verdens Gang newspaper reported that the suspect had previously been convicted of aggravated assault, illegal possession of weapons and on drugs offences and had also been investigated for attempted murder, but that case had been dropped. In one case, the paper reported, an appeal court ruling had referred to the man’s “obvious mental health problems”, the paper said. Hatlo said psychiatric problems could be a factor. “We have to go through his full medical history,” he said. The suspect’s lawyer, John Christian Elden, told NRK the killings were being treated as a terror attack. “I think that may be premature, but I understand the police do it that way,” he said. “I expect there to be an examination of his mental health condition.” First reports of the shootings, which happened at the London Pub, a popular bar for the LGBTQ+ community, a nearby jazz club, and a takeaway food outlet, were received at 1.14am, hours before the city’s Pride celebrations were due to start. Organisers said they had called off the march and all related events after receiving “clear advice and recommendations” from the police. “Now we will follow the police’s recommendations and take care of each other,” they said. “Warm thoughts and love go to relatives, the injured and others affected. We will soon be proud and visible again, but today we will hold and share Pride celebrations from home,” said Inger Kristin Haugsevje, the leader of Oslo Pride. A witness said the suspect, who was arrested within five minutes of the shootings, had looked “very determined about where he was aiming. There was a bleeding man lying on the ground,” she told Verdens Gang. Another witness quoted by the paper described “a lot of injured people on the ground who had head injuries”. An NRK radio journalist who was present at the time of the shooting said the shooter arrived with a bag from which he pulled out a weapon. “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,” Olav Rønneberg said. Norway’s prime minister, Jonas Gahr Støre, said Norway had “once again been hit by a brutal attack on innocent people. When the perpetrator started shooting, the world changed from happiness, laughter and love, to hatred, bullets and murder.” Støre added: “Even though we do not know that the queer community was the target, the queer community were the victims. We know many of you are scared, despairing and furious. We share that despair. We stand together.” King Harald said he and his family were “horrified by the night’s shooting tragedy … We sympathise with all relatives and affected and send warm thoughts to all who are now scared, restless and in grief,” he said.