There were some anxious moments for students and staff at Villa-Maria high school Friday morning.
Officials initially believed an alarm was pulled at the school around 10 a.m.
Police and ambulances rushed to the scene, but police later confirmed it was a false alarm.
The school was gradually evacuated as a precaution, and students were transferred to nearby Marianopolis College where parents were able to meet up with them.
The police operation ended at 2 p.m. when no evidence of an emergency was found at the school.
According to police the alarm system, which is connected to 9-1-1, signalled that an active shooter was present in the school.
Normally a person must enter a code on a panel at the school to transmit this message to police, but there is no sign that anyone at the school actually did this.
School officials will be investigating how the system malfunctioned, or if something else happened to trigger the alarm.
