An alleged threat at a Windsor school prompted an increased police presence Friday. The Greater Essex County District School Board said a message was sent to W.F. Herman Academy community Thursday night, but officials have not provided any further details as to the nature of the threat. Police are investigating. AM800 obtained a letter from the school’s principals, which says elementary students reported overhearing a violent threat from a student directed at the school during dismissal Thursday. Police were contacted and attended the school to investigate.