At least five people have been killed and two others injured in the Norwegian town of Kongsberg by a man armed with a bow and arrow, police said. Øyvind Aas, the police chief in the town, about 70km southwest of the capital, Oslo, told a press conference on Wednesday night that the attacker had been arrested and “according to our information, is the only person implicated”. Aas said there had been “a confrontation” between officers and the assailant, but he did not elaborate. Two people were in intensive care, including an off-duty police officer. Aas declined to comment on press reports that a police officer had been shot in the back. He said the attacks happened over “a large area” of the town and several crime scenes were involved. The acting prime minister, Erna Solberg, described reports of the attack as “horrifying” and said it was too early to speculate on the man’s motive. “I understand that many people are afraid, but it’s important to emphasise that the police are now in control,” she told a news conference. The prime minister-designate, Jonas Gahr Støre, who is expected to take office on Thursday, called the assault “a cruel and brutal act” in comments to Norwegian news agency NTB. The attacker’s motive was not yet clear, Aas said, but police were not ruling out terrorism. “One person has performed these actions alone,” he said. “It is natural to consider whether it is an act of terrorism. But the man has not been questioned and it is too early to come to any conclusion.” The suspect, whose age and identity police declined to disclose, had been taken to a police station in the nearby town of Drammen and no one else was being sought in connection with the attack. Norway’s minister of justice, Monica Mæland, was monitoring the situation. The Norwegian public broadcaster, NRK, said police in Kongsberg, a municipality of about 28,000 people, received reports at about 6.15pm local time that a man was walking around the town centre firing a bow and arrow. A “large number” of police, as well as helicopters, dogs and armed response teams secured the area soon afterwards, Aas said, and the suspect was arrested about 20 minutes later after a brief confrontation with officers. Eight ambulances and three air ambulances had been dispatched to the scene and Oslo university hospital and the local hospital at Drammen were on standby to receive victims. The shooting appears to have started in or near a Coop store in the city centre where there were several casualties, Norwegian media reported, citing regional government officials who said details were “still very confused”. Several other people were injured in different stores in the city centre, according to media reports. A Coop spokesperson, Harald Kristiansen, told NRK there had been “a serious incident in our store” but no employees were among the injured. “We are providing assistance to our colleagues and helping police with their investigation,” he said. “A lot of resources were sent from several places, including Oslo police district, the bomb squad, national police and emergency response teams,” Aas told journalists. “There is still a lot of police activity across the area. They are securing the various crime scenes … and have many witnesses to interview.” The VG newspaper showed images of an arrow that appeared to be stuck in the wall of a wood-panelled building. Kari Anne Sand, Kongsberg’s mayor, told the newspaper the attack was “a tragedy for all those involved. I have no words”. Sand said a crisis team had been installed in a hotel to support those affected. “We are doing all we can,” she added. “Right now it is a chaotic situation and there are a lot of rumours.” Shortly after the attack Norway’s national police directorate said it had ordered officers nationwide to carry firearms. Norwegian police are normally unarmed but officers have access to guns and rifles when needed. “This is an extra precaution. The police have no indication so far that there is a change in the national threat level,” the directorate said in a statement.