There is a new 911 feature called Reverse 911
The reverse 911 system was activated when brush fires broke out recently in San Antonio. The system is used by authorities to contact you of an emergency in your area. The city allows everyone to register cell phones and email addresses. Residents can register information on the city's website and pick how they want to be contacted. Options include phone calls, text message, email or fax.
For the direct link, click here http://www.sanantonio.gov/saNS/index.html