Harvard University evacuated on bomb report

America's leading school of Harvard University evacuated on reported the bomb presence in university.
According to U.S. media reports, the administration ordered of evacuation of four building of university to students as bomb reported.

It is mentioned in report that police is called on bomb presence, which start search operation to clear the university.
Police sources said they didn’t found any bomb till now. So it is never allowed to anybody  for entry in these buildings before completing the operation.