It happened just after 1:30 p.m.
The student and teacher were trapped under the small agricultural building but have since been freed.
Both have been taken to the hospital with non-life-threatening injuries.
According to Johnston County school officials, the two were inside the barn removing items so the structure could be torn down in the near future.
A county fire marshal was on campus doing a routine inspection and heard the collapse while several students heard it too and ran outside.
An investigation is underway to determine what caused the collapse.