Forest fire

In south California, very big forest fire broke out. This forest fire killed 6 people and 45 people were injured. Media report said this forest fire was the worst in the history. Fire burned 1660 square kilometers. this is correspond 70% of Tokyo. So A lot of people had to escape. The number of fugitives are as same as harricane "katorinu" . Therefore, president Bush announced the declaration of the state of emergency.Why this fire happened?? I feel that human cannot win nature. I hope this fire is stooped without delay.