At least 23 people have died in California wildfires

After days of raging wildfires that have left at least 23 people dead, authorities in California say emergency alert systems will be scrutinized.

Communities in the fire-prone state have an array of methods for alerting residents of danger, including text messages, phone calls, emails and tweets.

But in emergencies where a few minutes or even seconds can save lives, the notification systems have inherent blind spots.