Macdonald High School in Sainte-Anne-de-Bellevue, Que., says it closed on Thursday due to a potential security threat.
Posts on social media were circulating in the previous 24 hours about online threats targeting the school, but police told Global News on Thursday that the threats were unfounded.
Students were not yet at the school on Thursday when the threat was discovered.
Officials say the school shut down all classes and activities for the day as a precautionary measure.