If you have never had the opportunity to visit the Willis Tower in Chicago and stand on the SkyDeck, it really is an impressive site. It frightens many people but on Monday, visitors got a little more than they bargained for.

It seems as if the attraction was in need of some maintenance because the glass layer that covers the deck splintered into thousands of pieces. According to the Willis Tower, there was never any need for concern, as no one was in danger. The protective layer was simply doing what it was supposed to do.

The moment that the deck cracked was caught on video.

“There was a woman with two kids and they looked really pale and scared because the floor just cracked,” Pintado said.

The SkyDeck is found on the 103rd floor of the Willis Tower in Chicago. By design, it can hold up to 5 tons and about 1.5 million visitors come to see it each year. The covering that cracked is designed to protect the ledge from scratches.

This isn’t the first time that this has happened. It was also reported to have happened in May 2014 when Alejandro Garibay told a local news station that he evacuated the ledge when lines started forming in the glass.

There was also no danger to visitors in 2014.