Several people have been injured after a sword-wielding attacker entered a school in central Sweden on Friday, authorities said.

Fagersta municipality released a statement, saying that police had detained the suspect.

“An assailant armed with a sword has entered Brinellskolan [school] and wounded several people,” they said.

Swedish police said they responded to reports “regarding a case of ongoing deadly violence at a school in Fagersta” and confirmed one person had been taken into custody.

The municipality did not immediately disclose how many people were injured but Brinellskolan has about 450 students aged between 16 and 20, according to Reuters.

Police, ambulances and a helicopter were deployed to the school, while authorities searched the building. Other schools in the area were also placed under lockdown.

“Police are continuing to work ⁠at the ⁠scene with a number of different resources,” police said.

“The public is urged ‌to respect the roadblocks and listen to police instructions.”

Swedish Prime Minister Ulf Kristersson called it a “serious incident” and said authorities did not yet know what was behind the attack.

“We do not yet know what lies behind the act, but we know that the police are working very intensively,” he said.