The San Luis Obispo County Office of Emergency Services says its annual sirens tests were successful.
The office tested 131 Early Warning System (EWS) sirens Saturday at noon and 12:30 p.m. across San Luis Obispo County.
The sirens lasted about 3 minutes each.
They were installed as one of the requirements related to the operation of the Diablo Canyon Power Plant, but they can be used for any type of emergency.
If you hear the sirens sound outside of a scheduled test, you're advised to tune to a local television or radio station for information about the Emergency Alert System activation.
Click here for more information about the county's EWS sirens.