after reading that news story, i got to thinking about how you could rescue someone being trampled.
i came up with... (assuming you're right inside the door)
-run as fast as you can and jump on top or into the side of people, in an attempt to knock more people down.
-same as first one, only pushing a shopping cart.
-screaming bomb
-screaming gun
-shoot a couple shots into the ceiling, if you're carrying
-try to force the sliding door closed
-pull fire alarm
and i honestly don't think any of those would work very good. even if you started shooting, the people outside the door might not hear it over the crowd and threw the doors/windows.
and if you knock people down, its just going to pile up and the people on the bottom would end up in the same shape as the trampled guy.