The area near an uphill incline is considered a collection point for fuel and ignition sources, and it's possible a piece of debris fell into the tinder-dry brush early Thursday and sparked the fire, Piranio said.
This is possible because with the lasers, the location of the ignition can be in the center of the air-fuel mixture, rather than just the portion closest to it.
The fast-ignition technique is more like a petrol engine: first the fuel is compressed and only then is it ignited by a second laser pulse acting as a spark plug that is fired through a hole in the pellet.