Workers said they were told over a public address system that a bomb had been found inside.
The bombs that can be used against him are found later in the game.
Two other bombs were found that failed to go off.
No bombs were found in the school during any of the incidents.
A bomb was later found in one classroom, large enough to blow up the school building.
No bomb was found, and the members returned to the chamber a few minutes later.
The bomb, which did not explode, was found last Saturday by a group of children.
Over the course of a year, 126 rockets and bombs were found on the property.
The police searched the venue but no bomb was found.
None of the threats proved to follow through and a bomb was never found in any case.