The popular Skydeck attraction in Chicago scared tourists when they heard a loud "boom" and realized that a glass had cracked.
On Monday night, visitors of the Willis Tower Skydeck were frightened by the loud sound made as the protective glass of the popular ledge cracked.
A woman and two children were standing on the ledge at the time, said eyewitness Jesus Pintando according to NBC Chicago. They were on the site's 103rd floor.
Pintado described the sound like a "boom" and said the people looked "really pale and scared because the floor just cracked." He proceeded to record the incident and upload it to Facebook.
A spokeswoman for the tower, Terri Cornelius, assured the public that there was never any danger to guests despite the noise and the resulting fright.
He said the protective glass which splintered is "like a screen protector" for the tougher glass below and called what happened "minor cracking."
Cornelius said the glass was replaced the same night and by Tuesday, the Skydeck was back in business. The company typically replaces the glass on an annual basis.
A similar incident took place back in 2014 at the same Skydeck tower. At the time, four people stood within the glass enclosure located towards the building's west side.
According to NBC Chicago, one of those persons was Alejandro Garibay, who said it was a "crazy feeling and experience" to hear the glass cracking below them.
Again, a spokesperson, Brian Rehme, said the guests were never in danger. "This coating does not affect the structural integrity of The Ledge in any way," he wrote in a statement to the public.
The Skydeck remained open but the four Ledge boxes were immediately closed for inspection. They were able to reopen the next day. The Chicagoan Skydeck has been open since 2009.
A glass deck bridge in China also cracked underneath tourists' feet — but this time it was intentional. Thrill seekers looking for a real scare were happy to brave the daring see-through walk on the edge of a mountain.
The attraction, called the East Taiheng Glasswalk, is located in the Hubei province. As tourists walk, they will observe a cracking effect triggered by their movements over the glass.
The experience is meant to be a frightening one and has certainly created the desired effect in many. We hope the cracking glass is just a protective layer in China as well.