The incident occurred on Friday afternoon at the Brinell high school in the central Swedish town of Fagersta, which has about 13,000 residents. The school had just reopened after summer recess, and for some students, it was their first day.

Police told a press conference that the suspect was an 18-year-old man whom they shot and took into custodyon suspicion of murder.

Local police chief Tommy Alriksson said officers responded quickly to the school, which has 450 students ages 16 to 20.

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

Public broadcaster SVT, citing unnamed sources, reported the attacker, wearing a helmet and carrying a sword, was a former student at the school with a previous conviction for assault.

The local health authority said two victims were teenage boys who were severely injured. A third injured person was released from hospital.

Swedish Prime Minister Ulf Kristersson cancelled a speech he was due to hold on Saturday, news agency TT reported.

"Our thoughts are with all those affected," he wrote in a post on social media platform X.

Social Democrat leader Magdalena Andersson, whose centre-left coalition leads opinion polls for next month's parliamentary election, said: "All of Sweden stands together with Fagersta at this difficult time."