Looks really bad. Hope also that nobody was getting hurt. I was there also eating one time in the past. Did they tried to create a new real taste BBQ burger?
We'll see what the cause was, but that restaurant was closed for at least a couple days already when it happened. It was being "updated". So my best guess is that something went wrong with the updating. Other thoughts would be of a criminal nature, so best not to vent those.
There was no info that it was already closed for renovations, upgrades or repairs. I thought that some food started to burn from overheating. Interesting that more and more "renovations" are turning into a bigger mess.
When my gf read all the comments in her language, she said it looks like some electrical renovations started the fire. That's just gossip but where there is smoke there is fire.