Orange County Fire Rescue battled a fire at the Avanti Resort on International Drive in Orlando Sunday night.
Fire officials say the fire was likely started by lightning.
Witnesses in the area reported seeing strikes in the sky.
Then at around 6 p.m., flames were spotted from the hotel's roof.
Fire officials say 500 rooms were evacuated, but no one was injured.
As of about 10 p.m. Sunday, some guests were allowed back to their rooms.
Crews will remain on scene overnight to check for hot spots.
The state fire marshal is investigating.