Visitors at Chicago's Willis Tower had a scare Monday night after the protective layer of the building's skydeck cracked under their feet, WBBM reports.
The incident occurred on the skyscraper's 103rd floor, where the ledge's top layer, which covers the glass below, broke into pieces.
"There was a woman with two kids and they looked really pale and scared because the floor just cracked," witness Jesus Pintado told the station.
"I'm scared of heights in general so when I saw that happen, I was like nope, not going on," Karly Pintado, another witness, said.
A similar incident occurred in 2014, when a protective layer on the same floor cracked and frightened tourists.
That year, Bill Utter, a spokesman for the Willis Tower, told CNN that the ledge's top layer does, in fact, crack from time to time and dismissed any notion that the structure itself was compromised.
"The protective layer did exactly what it was supposed to do," he said.
Completed in 1974, the Willis Tower was known as the world's tallest building for almost a quarter of a century. Ten years ago, an observation deck with four protruding transparent boxes was added to allow visitors enjoy vertigo-inducing views of Chicago.