Lawrence-area cellphone users heard repeated, loud Amber Alert notifications when a 10-year-old Missouri girl went missing last week, but only one audible alert on Tuesday after a missing Texas teen was thought to be traveling on Interstate 35 near Lenexa.

The multiple audible alerts last week were a glitch, according to an official from the National Center for Missing and Exploited Children.

The alerts are shared through a system called Wireless Emergency Alert, which last year replaced a text message service that required cellphone users to register online and make an adjustment on the phone itself.

The new system, a partnership among the Federal Emergency Management Agency, Federal Communications Commission and wireless carriers, sends alerts to all wireless users in an affected geographic area. Alerts carry the same tone as they do on television and radio broadcasts, and are sent for emergency weather notifications, Presidential alerts and imminent threats.

“Glitches can arise when it’s the first time an Amber Alert is shared on a mobile device in that area,” said Bob Hover, director of special projects for the center. The glitch is now fixed, he said.

Cellphone users can turn the alerts off in the settings area of the phone.