LPT: If you see someone fall on an escalator, there will always be shut off buttons located at both the top and bottom by the hand rails.
I just experienced a situation where I saw an older gentleman fall on an escalator. Everybody immediately nearby panicked and watched or tried walking up the moving escalator in an attempt to help the gentleman up.
I ran over and hit the shut off button located on the bottom of the escalator by the right hand rail as fast as I could. Thankfully the older gentleman was okay, but suffered minor scratches on his arm, hand, and back.
It's important to know that shut off buttons are not universally on the right, but they are REQUIRED to be somewhere easily accessible on both the top and bottom, usually found somewhere near the handrail.