The fire quickly grew into a firestorm due to the 50 mph+ winds. Southern California is known for this phenomenon of dry winds that blow from the desert called the Santa Anas. They only affect certain areas, so the perfect combination of the winds + being in a fire prone area + having record rainfall the year before + being in a drought caused the fire to burn crazy fast with access to lots of brush (fuel).

If you don't stop it within the first 5 min, it quickly gets out of control. There's so much stuff to burn.