Police were called at around 9.10am after they were alerted to the threat.
As a precaution, to ensure student safety, the school was evacuated.
Cybercrime detectives and local officers have attended the school and have confirmed that this is a hoax and not a genuine threat.
The decision has since been taken to close the school to all pupils, after they were left outside for two hours while the situation was dealt with.
Pupils are being sent home on a year by year basis.
The school will be open as normal tomorrow.
Police are currently carrying out enquiries to determine the circumstances around the incident.