This morning, one of our neighbors asked my wife if we were ok, and said they saw an ambulance and fire truck up at the end of our driveway at 3 AM last night. We asked around and one of my friends who works with the fire department told me he was up putting it out last night. He described it as an "unattended camp fire". It wasn't just a fire someone failed to fully extinguish. It was a fire they just completely abandoned while it was still burning.
My guess is it was a bunch of kids out way past their bedtime and when the parents finally got in touch with them to demand they go home, they probably were in too much of a hurry to put it out. (Or at least, that's one of the more plausible explanations I can come up with.)
Not very cool considering the dry conditions around here.