The Willis Tower SkyDeck is one of the most popular tourist attractions in Chicago. Earlier this week, the protective layer covering the famous glass floor splintered into thousands of pieces, sending visitors scrambling for solid ground.

According to CNN, nobody was hurt and nobody was in danger, as the ‘protective layer did what it was supposed to do’. That might not be enough to calm the nerves of anybody who was there though. Chicago-area resident Jesus Pintado captured the harrowing moment on video.

Located on the 103rd floor, the SkyDeck attracts over 1.5 million visitors each year. The glass-bottomed ledge is designed to hold up to 5 tons. The last time the protective layer cracked was May 2014, inducing a similar panic from visitors. [source]