Why didn't the tornado sirens go off in the Austin area during Monday's tornado warning?

WILLIAMSON COUNTY, Texas (KXAN) — Videos from across Central Texas captured the tornado outbreak on Monday. One video from Round Rock showed people being caught off guard and running for cover.
Many KXAN viewers questioned why the tornado sirens did not go off on Monday. KXAN asked Williamson County Judge Bill Gravell for an answer."I think the greatest resource we have is our local media and our local meteorologists. Sirens are an option, I don't know if they are the best option today, in