There is a mark on the log where saw can be started and has to be shutoff.
Channel 13 had a really good angle. Saw that last night glad they are ok you were in the end of 13s videoHere is a pic and news clip from this last week end. Big Bill and Tractor Dave get lit up. I talked to Bill a bit ago and they will both be O.K. Dave (the tall one) took the worst of it and only spent a short stint in the hospital.
http://www.king5.com/localnews/stories/NW_092908WAB_chainsaw_fire_SW.c4086149.html
My guess would be a rapid, uncontrolled oxidation of highly volatile liquid fuel.
Glad he's OK.
On a side note, You all should know that I am on strike (Boeing)... and don't use this puter to much, so I have not been posting as regular.