All-clear given at locked-down Swiss university

Swiss authorities have given the all-clear after locking down a university building in Zurich due to an anonymous threat.
Zurich police said today that they had found no danger at the Zurich University of the Arts. Thousands of students had been told to stay in their classrooms as police searched the building after the anonymous threat came in.
They say the building will remain closed for the rest of the day but that classes will resume tomorrow.
No further information was released and police say the investigation is ongoing.
Police responded to another alarm at the school a week ago but it turned to have been accidentally triggered.