Im sure it mentions in the POH that you should shut off the fuel and isolate the main battery after a heavy landing...
So why are the landing lights still on?
Nice of them to leave the battery on while avgas poured out.
I'm only guessing, but I reckon the pilot and occupants are probably in a state of shock at this stage, probably also injured and not really thinking straight. I doubt there were any other pilots around so it is unlikely that anyone would even know what a master switch was, let alone find it and know it needed switching off. In an ideal world someone would have started moving everybody back to a safe distance but the ideal world doesn't exist just after such an accident - even bystanders find themselves in a state of shock and it takes a while for everyone to come to their senses.