What are an event that is shocking in the Phantom of Opera?

One shocking event in the Phantom of the Opera occurs during the opera's masquerade ball. While Christine Daaé is performing on stage, the Phantom makes a dramatic appearance by descending from the ceiling in a glittering chandelier. The chandelier crashes to the ground, causing chaos and panic among the audience. This shocking event sets the tone for the rest of the story and establishes the Phantom as a mysterious and dangerous figure.