“All students will be searched for dangerous objects at the entrance,” police spokesperson Manfred Etzel said, adding there would be a heavy police presence in the area.
The building on Wendenstraße was closed on Wednesday while police searched for possible bombs with the help of tracking dogs as officials attempted to trace the person who sent an anonymous email with threats of violence.
Students were sent to other schools in Erfurt.
The threats came some eight years after the homicidal massacre in the same city at the Gutenberg Gymnasium high school that left 16 dead. In April 2002, a 19-year-old former student went on a gun rampage and killed 13 teachers, 2 students, and a police officer before committing suicide.