Two vocational colleges in Thun, canton Bern, have closed early for the end-of-year holidays after a written threat that a "killing spree" would happen on Thursday.
The two establishments, part of a complex, were shut down on Tuesday evening after an anonymous inscription was found a week ago warning of an attack on December 20.
Despite the fact that it is impossible to determine if there is any real danger, the police and the college authorities decided to act given the outcome of other cases abroad.
In November, two German schools were closed temporarily because of threats and an 18-year-old killed eight people at a Finnish high school. In April, a student killed 32 staff and other students at Virginia Tech in the United States.
The cantonal police have put 30 people on the case to find the author of the threat.
Around 700 students present were to told stay away as of Wednesday and others have been warned. The colleges will be officially closed down until the end of the week, but because of the holidays, this means no one will be present until January 7.