Yeah, the video from the Skyliner in the article @horsesboy posted clearly shows it's a backstage structure. Looking at satellite images, it definitely looks like a walk-in cooler to me.
Glad it was just that and not something guest-facing. Hope no one was hurt!
There was also a small brush fire at the Saratoga Springs resort a few days ago possibly caused by a cigarette. Orlando and Central Florida are in a high drought area right now and prone to wildfires.