When there is a police presence in a neighborhood that will/could affect others, the Police can send out a Reverse 911 call to alert those in the area. They don't just call though, you have to sign up for this service.
This past week I got a call at 11:41 pm and said there was a heavy police presence in my area, and to be sure I took shelter, and was sure the doors and windows were locked. If you did not have to leave, stay in! They called again at 1:19 am to let me know the incident had been concluded, and there was no danger.
I signed up with my home phone and my cell. They called on my cell and left texts messages also, but I turn my cell off at night, so got the message on my home phone. If I was out and about during the day, I would want these urgent messages on my cell. The Police Department has sent out messages through this service for Amber Alerts or At Risk individuals that have wondered away.
Have you signed up for this service?