A teenage boy was arrested on Wednesday on reasonable suspicion of making a serious unlawful threat against a group.
"There is no reason for concern or any ongoing threat linked to the case," said Public Prosecutor Joel Henning, adding that the police are carrying out "broad, methodical work" to build a picture of the incident.
"There is a lot being done today; several interrogations are taking place. The suspect will also be questioned again," Henning said.
The teenage boy had been missing for the past few days, but was found around noon on Wednesday. School closures affected thousands of students in Borlänge's municipal preschools and primary and secondary schools.
