Firefighters on the scene told ABC11 they responded to a call of a bomb threat and immediately evacuated the library while N.C. State police searched the building.
Police say a staff member got a call from an unidentified caller saying a bomb was in a library restroom.
However, nothing was found, the all clear was given, and the library re-opened at 5:30 p.m.
The case is under further investigation.
Anyone with information about the incident is asked to contact the NCSU Police Department at (919) 515-3000.