At least three guests were injured Monday night after an iceberg wall collapsed at the Titanic Museum Attraction in Pigeon Forge.

The three guests were taken to area hospitals and their injuries are unknown at this time, the museum’s owners, Mary Kellogg Joslyn and John Joslyn said. It wasn’t immediately clear what caused the collapse.

“Needless to say, we never would have expected an incident like this to occur as the safety of our guests and crew members are always top of mind,” the owners wrote on a facebook post. “We take pride in the quality of our maintenance and have measures in place to ensure that appropriate safety guidelines are upheld.”

The attraction was closed following the incident, they added.