We had a burn barrel when I was a kid in Oakridge. We used it a lot. And one of the things that dad and mom drilled into our little brains was that gasoline and/or diesel or any combination thereof and open fires did not mix. Or that if the did the results could be unpleasant to say the least. I seem to remember a little gas and a lot of newspapers to get the trash fire going.
This guy probably got the fire going, didn't react fast enough and it traveled right up the fuel stream, into the can and whoosh, you've got a Molotov cocktail on steroids.