Some visitors had a scare when the protective layer of the SkyDeck at the Willis Tower cracked Monday, splintering into thousands of pieces, CBS Chicago reported. A video shot on the 103rd floor showed horrified visitors looking at the crack from the safety of the building.

The Willis Tower, however, assured visitors that none of the guests were in any danger, saying only the protective layer cracked and the glass floor below it remained intact.

"There was a woman with two kids and they looked really pale and scared because the floor just cracked," witness Jesus Pintado told CBS Chicago.

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"I'm scared of heights in general so when I saw that happen, I was like nope, not going on," another witness, Karly Pintado, said.

The Ledge is built to withstand five tons of pressure and can hold 10,000 lbs. Approximately 1.7 million tourists visit it each year. The floor also cracked in 2014, generating a similar panic.