First, so glad all are safe. A terrible mess.
Now regarding your comments that the fire appears to have started on top of the engine.
There's a plastic fuel line coming into the engine fuel filter there. Squirrels love to chew on this, as they chewed holes in mine while I owned my 2011 Ford F-350 w the 6.7L diesel. Lucky for me I was only in my driveway when I started the vehicle, but WOW for an immediate over-powering diesel smell. Shut my truck off immediately upon the smell, and fuel dripping all over the place.
I can only imagine how much fuel would have been pumped out had I been driving, as you were, when one of these chewed on spots finally gave out and released fuel, and then not being able to shut down or even stop the vehicle immediately.
Again, so glad all got out safely.