Big Island sirens pass test

A Hawaii Civil Defense Warning Device, which sounds an alert siren during natural disasters, is shown in Honolulu on Wednesday, Nov. 29, 2017. The alert system is tested monthly, but on Friday Hawaii residents will hear a new tone designed to alert people of an impending nuclear attack by North Korea. The attack warning will produce a different tone than the long, steady siren sound that people in Hawaii have grown accustomed to. It will include a wailing in the middle of the alert to distinguish it from the other alert, which is generally used for tsunamis. (AP Photo/Caleb Jones)

The first use of air-raid warnings on Hawaii Island in decades appears to have worked as planned Friday, according to Hawaii County Civil Defense.