At this point I don't believe there has been any information presented to indicate that anyone (vendor or patrons) violated any rules. The news I read stated that the truck appeared to have experienced a mechanical failure. Unless the investigation reveals some sort of neglect in regards to the maintenance of the truck then I'm not sure that anything should be done.
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"There is not a man of us who does not at times need a helping hand to be stretched out to him, and then shame upon him who will not stretch out the helping hand to his brother." -Theodore Roosevelt