Word in the Lounge is that Irvington called it today...no school so probably their siren.
Often it's just a drill. They announce them campus-wide, but probably not to the general community. I'll try to remember to post here next time they announce one.
Also - they don't sound an alarm for canceled classes - they e-mail and text all employees and students
when S.H. sounds it's alarm does that mean that they have cancelled classes?