GOLDSBY, Oklahoma - The National Weather Service has given a preliminary rating of EF-1 to the tornado that hit Riverwind Casino Saturday night. Riverwind officials say it caused the worst damage the casino has ever seen.

Videos posted to social media show an array of waterfalls pouring down onto Riverwind patrons after the tornado ripped across the building. Governor Mary Fallin was among those attending a Beach Boys benefit concert when the storm hit. She told News 9 right after it happened, “I looked up towards the balcony and there’s this huge flood of rain coming through the roof into the concert hall.”

The governor says she received a warning on her phone about the impending tornado, but the casino did not have time to get employees and guests into safe zones before it arrived. Spokeswoman Kym Koch says, “Our crews were watching, making sure that we were taking all of the necessary precautions, but we didn’t get a warning until the tornado was upon the building.”

800 of the 2,700 electronic gaming machines on the casino floor shut down in the flooding, and crews spent all day Sunday working to get them back up and running.

Meantime, the attached hotel had to evacuate for the weekend, with windows and a large piece of the building's facade blown away. “The power is back on,” Koch reports, “but we’re still assessing damage and we’re taking care of the patrons who are booked there for the next night or two and putting them up in another hotel.”

The hotel expects to start booking guests again later in the week.

The kitchens are also out of commission for the time being, but Riverwind brought in a food truck to help serve hungry customers, who are still showing up to the casino in normal numbers despite the debris.

At this time, 60 machines remain inoperable on the casino floor as they continue to be assessed for damage.