My kids go to a TX university where they have a fairly robust emergency broadcast system for students who opt into the service. They are texted when 'authorities' (there are validation cycles/sources) have determined an emergency situation is in process notifying students of an active situation (either active shooter or lockdown for violent person escape/at large).

I know Waze does have some features with other traffic or EMS emergency notification features, but I think there might be a valid case to use the Government and Public Safety alert systems for people who are within a mile of an active shooter situation. (Or whatever distance). If verified information through Emergency systems tracked to GPS on mobile phones and apps, an emergency alert should sound displaying the map location where the activity is taking place.

Sadly, it has come to the point in this country when going shopping or to a concert may involve an emergency situation. Waze has some available technology to build out this idea quickly (I believe) and also has business relationships with other companies to send emergency messages through devices if the Waze app is not open.