This cell phone app would alert authorities of an Active Shooter with One Click, and include; Name of Sender (verified), location, etc. The App would immediately silence (sound and vibration) of senders phone and keep line open.
There would be no need to speak to 911 operators to determine type of emergency, etc.
To have the app, the individual would have to apply to DHS or police force with Name, Address, Driver's License Number before app would be activated.
If in an Active Shooter environment, this immediate click of the phone would send data transmitting without the need to do anything else.