A California family visiting the Willis Tower in Chicago said they heard the glass flooring on its 103rd floor Skydeck begin to crack Wednesday night while they were taking in views of the city.
A spokesman from the building said the sound came from the coating on the glass and the family was never in danger, The Chicago Sun-Times reported.
“Occasionally this happens, but that’s because we designed it this way,” he told the paper. “Whatever happened last night is a result of the protective coating doing what it’s designed to.”
Moments before the family walked out onto the Skydeck, they say they were reassured by staffers that the window flooring was unbreakable.
“I had my palms on the floor and I could feel it cracking,” Alejandro Garibay, 23, told The Chicago Tribune. “Honestly, I was in shock, in disbelief. I was scared.”