The Toronto District School Board says Duke of Connaught Junior and Senior Public School could remain in a hold and secure into Friday.
The hold and secure began on Thursday, as police investigated an unspecified threat to the school.
In a letter sent home to parents, the board said, "While police did not find anything of concern at the school, they are continuing to investigate. As a result, we are being advised that it is possible that we may begin the day tomorrow in the same situation."
Classes went on as usual Thursday but students and staff were kept inside and the exterior doors of the building were locked. Students were released when their parents arrived to pick them up. A number of evening and outdoor events were cancelled.
The letter says updates will be provided to parents "as needed" via email and through the school's website.
