The incident took place on the building’s 103rd floor, where the Skydeck is located for tourists to get a view of the city and Lake Michigan.
"There was a woman with two kids, and they looked really pale and scared because the floor just cracked," Jesus Pintado, who captured footage of the incident, told CBS Chicago.
“I’m scared of heights in general so when I saw that happen, I was like nope, not going on,” another visitor, Karly Pintado, told the local news station.
According to a building spokesperson, no one was injured, and the ledge was immediately shut down following the incident.
"The protective coating which acts like a screen protector for the ledge experienced some minor cracking," a spokesperson told WTHR Monday. "We replaced the coating last night, and the ledge is open for business as usual."
This is not the first time that the ledge’s protective layer has shattered. Back in 2014, the observation deck was closed after the protective layer cracked while visitors were enjoying the view of the city.
According to a spokesperson for the tower at the time, "[The top layer of the ledge] is designed to crack when somebody drops something on it," DNA Info reported. "It's not structural. The top piece is protective."