The threat sent schools in Grandview and Mabton into lockdown for part of the afternoon.
Administrators said the parents came to take the student home.
The threat came from a man off campus and that he's the boyfriend of the student's sister, according to investigators. They think he's somewhere in the Mabton area.
Students were left with questions and in shock.
Despite the lockdowns, students at the schools were released at their normal times.