PIKESVILLE, Md. (AP) — Maryland State Police say Amber alerts are now being sent to all cell phones designed to receive wireless emergency alerts.

The alerts are used to help find abducted children. State police say they have been instrumental in the safe recovery of 602 children nationwide. Previously, cell phone owners only received alerts if they had visited a website and opted in to the alert system. State police say users can shut off the alerts by changing the notifications settings in their cell phone or contacting their service provider.

The alert uses a loud tone similar to emergency alerts on radio and television. A text message up to 90 characters is also sent. Cell phone owners who travel outside of Maryland will receive alerts issued in the area they are visiting.

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