In just a few terrifying hours, the Mountain Fire became the most destructive blaze in Southern California in years. The conditions were ripe for disaster, and neighborhoods had few defenses. Here is what happened.

Now covering over 20,000 acres the blaze has grown significantly over the past day. It is so far only five percent contained and has destroyed 132 structures.

Calmer winds helped California firefighters battle the once out-of-control Mountain Fire on Friday as they continued to defend homes from the destructive blaze, officials said.