An 18-year-old man armed with a sword attacked a school in central Sweden on Friday, killing one person and seriously injuring at least two others, police said.

Police Chief Tommy Alriksson said the suspect was arrested after the attack at Brinell School in Fagersta, a town northwest of Stockholm.

Police fired shots while apprehending the suspect. Authorities did not immediately say whether he was wounded, but confirmed that he remained in police custody and was not taken to a hospital.

The attack occurred while classes were underway at the school, which had around 400 to 500 students at the time. Authorities have not disclosed a possible motive.

"We have no reason at this time to believe that there are multiple perpetrators," Alriksson told reporters, adding that the investigation was continuing.

National police said investigators had conducted two searches of properties linked to the suspect and planned to question a large number of witnesses.

Alriksson said authorities were withholding some details to avoid affecting witness accounts as the investigation progresses.

According to Sweden's TT news agency, Vastmanland County officials said the two seriously injured victims were boys aged between 12 and 17. Authorities did not immediately release information about the person who died.

Police spokesperson Pelle Vamstad told TT that officers received an emergency call shortly after noon Friday. A large area around the school was sealed off as police responded to the incident.

Several nearby schools were also placed under lockdown, while roadblocks were established in the area, officials said.

Swedish Prime Minister Ulf Kristersson expressed sorrow over the violence in Fagersta, which occurred shortly after students returned from their summer break.

"We do not yet know what lies behind the act, but we know that the police are working very intensively," Kristersson said in a post on X. He added that his thoughts were with everyone affected.

Fagersta's municipal authorities opened a crisis center at a nearby sports hall to provide support following the attack.

Vastmanland County officials said many people had been affected by the incident, with police, firefighters and health care workers involved in the emergency response.