A 17-year-old girl has been killed in a sword attack at Brinell School in Fagersta, central Sweden, police have confirmed. Two boys, aged 12 and 17, were also seriously injured, while another person sustained minor injuries in the attack on Friday afternoon.

Police arrested an 18-year-old man at the scene and are treating the incident as murder and attempted murder. Authorities said officers fired shots after arriving at the school but did not disclose whether the suspect was hit before he was detained. Local media reported that the suspect was wearing a helmet and may have previously attended the school.

The attack occurred shortly after students returned to school following the summer break. Investigators have conducted two searches of properties linked to the suspect as they work to establish the circumstances and possible motive behind the violence. The region was placed under a state of emergency on Friday, but the measure was lifted on Saturday.

Swedish Prime Minister Ulf Kristersson and opposition leader Magdalena Andersson visited the school on Saturday, where flowers had been placed in memory of the victims. Kristersson described the incident as serious, while King Carl XVI Gustaf said he received the news with “dismay and sadness.” The school has nearly 500 students and is located about 170 kilometres northwest of Stockholm.