I read on the news that it was in an old warehouse, with a bunch of artsy clutter everywhere. Apparently, the party was happening on the second floor, and the only staircase was a makeshift one built out of old, wooden pallets. You can imagine how quickly that might have been destroyed depending on where the fire started, trapping a lot of people on the second floor:
http://www.nbcbayarea.com/news/local...404793415.html
Really gut wrenching.