The Hindenburg Disaster From the Reason Perspective

The hydrogen inside the ship was clearly the main fuel source. The question is, what set that gas off? And you could propose multiple explanations. Could it have been someone in the smoking compartment? Could it be lightning? Or sparks from the engine? Or sabotage, like a om planted on board the ship? Even once we've determined what the cause was, is there more to the story? Was there a cover up after the disaster? Was it just a freak accident that nobody was responsible for or was it something that had been foreseen?