People might be surprised at how many 'Fire Bugs' there are in our society. Meaning, arsonists. They are starting fires all the time, just for the thrill of watching them turn big and burn everything in sight, for hundreds of miles.
Many of the very large burning areas we have had in the past were started at several different locations, by the same arsonist. So what you may have seen is an arsonist making the first fire he started, into one that would cover miles of acreage.
It's not uncommon, according to firemen I've known, for arsonists to do this.
Sickening, isn't it?
I heard some of those firebugs become firemen so they can see more fires, as well as eat the fine fine food prepared at the station