For the first time, in California, an Amber Alert was issued to California residents via text message.

The Amber Alert was issued after Christina Anderson’s suspected killer, James Lee DiMaggio, allegedly kidnapped her two children: Hannah Anderson, 16, and Ethan Anderson, 8. The alert was vague and only included information about DiMaggio’s blue Nissan and his California license plate. The alert did not describe the circumstances surrounding the emergency.

The 10-second, high pitched alarm, that sounded with the message, irritated and even angered some customers. The producer for KQED Science, Craig Rosa, says he was in his car along with his wife when both of their phones started buzzing “with an alert 10 times louder than any other alert on the phone. We had no idea what it was. Almost ran off the road trying to shut the things off.”

People complaining about the Amber Alert on their phone. I'm sorry for warning you of children being kidnapped in your area. #igiveupsociety

— valerie blah (@ms_yvette_blah) August 6, 2013

Many of the newer phones are already set up to receive the Wireless Emergency Alerts that look like text messages but are free, which means that customers must contact their cell phone service provider to opt out of the program. If they choose not to opt out, customers will receive alerts that are tailored to their geographic region.

The participating service providers include AT&T, Cellcom, Cricket, Sprint, Nextel, T-Mobile, US Cellular, Verizon Wireless and Bluegrass Cellular. The alerts are not based on the cell phone numbers; they are determined by the the cell phone’s proximity to the cell phone towers within a certain location. CHP spokeswoman Fran Clader said, “If you’re from Texas and that’s where your phone number is based and you’re traveling in California at the time of the Amber Alert, you’ll receive the text message about the Amber Alert in California on your Texas-based phone.”

If you didn’t receive the alert on your phone, you can contact the homicide detail at (858) 974-2321 or San Diego County Crime Stoppers at (888) 580-8477 if you have any information about the location of Hannah and Ethan.