One person was killed, at least three others were injured after an 18-year-old armed with a sword targeted a high school in central Sweden on Friday before police shot and detained him, authorities said, as reports emerged that the suspect was a former student with a previous assault conviction.

The attack unfolded Friday afternoon at Brinell High School in Fagersta, a town of about 13,000 people. The school had just reopened after the summer break, and for some students, it was their first day back.

Police said at a news conference that officers responding to the school shot and subdued the 18-year-old suspect before taking him into custody on suspicion of murder.

Local police chief Tommy Alriksson said officers entered the school shortly after arriving at the scene.

"The first patrol entered and let us know that the perpetrator was subdued with gunfire," Alriksson said.

Swedish public broadcaster SVT, citing unnamed sources, reported that the attacker was wearing a helmet and carrying a sword. It said he was a former student at the school and had previously been convicted of assault.

Local health authorities said two of those wounded were teenage boys who suffered severe injuries. A third injured person was released from the hospital.

The violence triggered a major emergency response and a five-hour lockdown at the school, which has about 450 students between the ages of 16 and 20. Several other schools and public buildings in Fagersta were also initially placed under lockdown.

One student, Nellie, said the school day had begun normally before she saw an injured person covered in blood and police officers rushing into the building.

Another student, Abdulrahem Salmo, told SVT he saw a victim with a bloody wound to the arm before students fled and contacted police.

Fagersta Mayor Asa-Marta Sjostrom said the attack had shaken the small community and that authorities were focused on supporting students, school employees and others affected by the violence.

Swedish Prime Minister Ulf Kristersson canceled a speech scheduled for Saturday following the attack, according to Swedish news agency TT.

"Our thoughts are with all those affected," Kristersson said on X.

King Carl XVI Gustaf said in a statement released by the royal household that he received news of the attack "with dismay and sadness."

Social Democratic Party leader Magdalena Andersson, whose center-left coalition leads opinion polls ahead of next month's parliamentary election, expressed solidarity with the community.

"All of Sweden stands together with Fagersta at this difficult time," she said.

Police were also investigating a TikTok account potentially linked to the attack, according to Swedish newspaper Aftonbladet. The account reportedly posted an image of a sword about 20 minutes before the violence began.

Dagens Nyheter reported that details visible in the background suggested the image may have been taken inside a restroom at the school.

Before the month-old account was removed Friday, it contained videos referring to two previous episodes of mass violence in Sweden as well as Norwegian far-right mass murderer Anders Behring Breivik.

The attack comes amid memories of previous deadly violence at Swedish schools. In February 2025, a gunman killed 10 people at a school in Orebro before killing himself in Sweden's deadliest mass shooting.

In 2015, a masked attacker armed with a sword killed a teaching assistant and two students at a school in Trollhattan in western Sweden before police shot him dead. Authorities later determined that the attack was racially motivated.