What are the emergency alert system in schools?

thanks

You interested me, I didn't even know that my school has such an alert system, although I try to be attentive to information that is new to me. I must have been so busy looking for this resource https://www.academicghostwriter.org/ for my ghost writer college papers that I missed it. But I will ask my classmates what they know about our electronic notification system. I'm interested.