Dozens of Serbian schools on Wednesday received bomb threats, the education ministry said, amid security concerns following two mass shootings early this month, including one in an elementary school.

The education ministry said 78 elementary schools and 37 high schools in Belgrade received warnings by email early on Wednesday that explosive devices had allegedly been planted. Classes were postponed and students evacuated as police checked the buildings. There have been no reports that bombs were found in any of the schools, and police are yet to issue their report.