Although not the reason, it's a good thing our cats are in carriers in the backseat of the truck when they're with us. All real valuables are in there, too, so grabbing them wouldn't take much time. As for disconnecting the rig to save the truck, depends on the actual situation at the time and how you react to an emergency. Some people will jump into action, others will freeze. Might be enough time to disconnect, might not. My training says to do a quick size-up and determine a course of action. The course of action may be to do nothing at all (to save the truck).
From the photo, it appears that the rig has been burning for some time, it didn't just explode into flames like that.