A report of a man entering the Tinto Drive school building at lunch-time on Tuesday send shock waves through parents when they later learned of the intrusion.
The intruder was confronted by a member of the school’s senior management team and the school-based police officer.
According to a school spokesperson the intruder was “removed swiftly and safely” and no pupils or members of staff were hurt.
The school stated: “We fully appreciate the concern such an incident can raise within our school community. We would reassure all pupils, parents and staff our systems and procedures worked correctly.”
A Police Scotland spokesperson said: “We can confirm a 21-year-old man has been charged in connection with threatening and abusive behaviour in Tinto Drive in Grangemouth on Tuesday, May 4.
"A report will be submitted to the Procurator Fiscal.”