Google has partnered with Nixle, a service that law enforcement agencies can use to release emergency information to people in their jurisdictions who sign up for the alerts.
The alerts will appear when someone uses Google in an area with an active alert or searches for a place that has an active alert.... Nixle adds "hyper-local" police information...
This may kill a few searches for site owners when there is an emergency in an area they dominate but overall it seems like a smart way for G to contribute to local communities and get a jump on breaking news.
Maybe in high crime areas we'll end up with website owner-vigilantes who go out to fight crime to remove alerts from their SERPs.
[edited by: Robert_Charlton at 2:27 am (utc) on Mar 30, 2013]
[edit reason] added clarification [/edit]