A police media spokesman said at least two police units arrived at the school and spoke with the principal and students who told police the balaclava wearing man was acting suspiciously on school grounds.
Police will put on extra patrols at the school over the next few days.
Police were called to the school at 1.20pm.
An earlier note from the school said it hoped it was a false alarm, but was "erring on the side of caution".
"We are pleased with how our staff and students have responded to this process and will always take the cautious approach with regard to such reports."
The school finishes at 2.30pm, but parents were advised the event could disrupt school pick up.