The Seminole case seems to be quite a bit different than the usual pranks by students in the past. Different callers making threats within minutes of each other. They certainly got the attention of the FBI who is now involved. Also there's a reward ($10,000 last I saw) for info. I suspect they're not telling everything about the threats, but something triggered the Feds to get involved.
Times have certainly changed, haven’t they? There are no such things as pranks.
FBI involvement and a $10,000 reward (which is not chump change) is enough for worry.