This month a blind man was walking inside the Metro station in Bethesda, Maryland, near Washington, D.C.. He was using his cane but did't realize he was standing at the edge of the platform. Then he stepped off the platform and fell onto the tracks below.
Immediately, five total strangers realized what had happened and rushed to save him. He managed to stand up, and they grabbed him by his arms and yanked him back onto the platform just in time. Another train was pulling into the station, and they only had 20 seconds to spare, but that was enough.