Do we know the cause of this fire? Maybe I'm missing it, but I can't seem to find any mention of it in the article.

Quite frankly, with that level of destruction fire investigators have their work cut out for them. There are times when there is just too much damage to ever pinpoint a cause.

Good point. It just sems suspicious to me.

It is very rare to see a fire in a developed area to have that much destruction. In today's world, someone is always awake, has a cell phone, etc., etc. It's apparent that the fire burned for quite some time before the fire department was notified.

I'm sure that after forensics are conducted a cause will be released. Sometimes fire causes aren't always cut and dry.

I know one of the neighbors and she didn't see anything when she looked out her window when doing her nightly check around 11:30.
Fires can smolder forever and when oxygen is supplied (burns through a wall, window breaks, etc.) it can go very quickly. I used to run with a ladies auxiliary and took a few basic firefighting classes years back!
God bless the family!