What happens if the house burns while in middle of rehab?

[Andrew Glenn]

Temple: House intentionally set on fire.
http://www.kwtx.com/content/news/Temple-House-intentionally-set-on-fire.html
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Short version for those who don't want to click: A house was intentionally set on fire. It was vacant and in the middle of a remodel. It burned to the ground, so it was a total loss. 
Let's say I buy a house and I'm in the middle of a rehab and something like this happens. Let's assume I didn't burn the place, too. :). Homeowners insurance would probably cover the structure, but what about materials inside? What about when I throw a HML into it? 
I think my liability for the HML would be limited to what I had drawn up to that point, but I would love to hear perspectives.
Full disclosure: this wasn't my house nor anyone I know, and I don't currently have an active project where this is a pressing concern. I'm just curious before my first cup of coffee for the day.