Wurzen (dpa/sn) - Four teenagers were responsible for the large police operation at two primary schools last Friday in Wurzen (Leipzig district). The 13 and 14-year-old boys had called the respective school administrations and made threats, the police said on Wednesday. The emergency services then searched the building but found nothing dangerous. A helicopter and several police dogs were also used. It is now being determined, among other things, because of the disturbance of public peace through the threat of criminal offenses.