The hold and secure has been lifted for schools in the Trillium Lakelands District School Board.
This morning, TLDSB put all of its schools into Hold and Secure after a threatening message was made over social media to the board.
The OPP has confirmed a 16-year-old Gravenhurst man was arrested just after 11:00am for allegedly being responsible.
Police say there is no ongoing risk to school safety.
(With files from James Bowler)