There's a police presence Thursday at North Lambton Secondary School in Forest.
The Lambton Kent District School Board said the OPP is investigating a potential threat after it was reported that a student attended the school, allegedly armed with a weapon.
The board is assuring parents it takes all concerns about student and staff safety very seriously.
Lambton OPP was notified immediately after school administration became aware of the possible threat on Wednesday.
Director of Education Jim Costello said the board followed the Safe Schools Protocol to ensure the safety of all students and staff.