At this point the details are not totally clear about how many people were injured in this event, but a mass casualty incident (MCI) was declared.
I would have thought that the highway would be an excellent firebreak, instead it proved deadly. I'm guessing that blowing and burning embers were able to get into engine compartments and set the fuel systems on fire, to include those on a car carrier truck.
It is another example of how fast fires can move and your best defense is getting out of the disaster zone as quickly as possible. By the time this is posted on Monday I'm sure there will be more details on the event.