Bones Zoot Zooter 1937 Packard Burns!

Jim “Bones” Noteboom has been building hot rods since the age of 15. His work was on the cover of car mags since he was 19. You don’t get on the cover of Car Craft or Rod and Custom without doing outstanding work. With that brief introduction you need to brace yourself for what follows.
We all assume that when we put our prized vehicle in an enclosed trailer and hit the road it is safe. Our Trailer Queen is valuable and must be protected, right? Maybe we just want to keep the miles off the car and towing helps do that. You have it spotless top and bottom and want to keep it that way. Well, think twice. A trailer is not always the safest place. I was once told by an insurance agent that more collector cars are damaged on trailers than on the street; hard to believe but understandable.
Bones and his wife were on their way to the Sacramento Autorama. When they neared Stockton on the Interstate they became aware that their trailer was on fire. Not only the trailer but also the Zoot Zooter 1937 Packard hot rod! Bones, his wife and the tow truck escaped but the Packard did not.
These photos are hard to look at but let them be a reminder to each of us to take that extra step of safety anytime we put a car in or on a trailer.
were you or insurance people able to determine what started the fire ?