Stockholm: Authorities ordered 16 public schools to shut in the central Swedish town of Borlange on Wednesday after receiving a threat of violence, officials said.
Private schools also kept their doors closed after being told of the threat.
"The decision is a precautionary measure due to a potential threat of violence against school activities," the Borlange municipality said in a statement.
It listed 16 municipal pre-schools, elementary and secondary schools that were to remain shut for the day. A number of private schools decided independently to close.
Police said in a statement they had received tips about "threats directed at schools in Borlänge".
"The police have opened a preliminary investigation into serious unlawful threats against a group. No one has been detained, and it is too early to say whether the threat has any substance or not," police said.
Borlange, a town of about 45,000 people, is some 200 kilometres (125 miles) north of Stockholm.
Police were to hold a press conference at 11:00 am (0900 GMT).
Attacks on schools are relatively rare in Sweden.
