Police evacuated Fuquay-Varina High School on Monday morning after the school received a bomb threat, then a fire alarm sounded as students were being allowed back into the building.
Police said after the threat was made to school administrators.
"At this point we do not have information that leads us to believe this is a credible threat, however given the importance of the protection of students, teachers, faculty and our community we are investigating this threat seriously until evidence proves otherwise," police said.
Then, as students were going back into the building a little after 9 a.m., a fire alarm sounded.
Police initially said they were reviewing security-camera footage to see whether someone had pulled the alarm.
Shortly after that, however, a police Facebook post said firefighters determined that "the fire alarm has malfunctioned due to a sensor issue. This is being addressed and additional alarms may occur while repairs are occurring."