Elevator dangers

We've all heard of people (or been the one) who got stuck in an elevator when the power goes out. We see in movies when someone gets an arm or leg stuck in the door as it shuts. Or maybe just a piece of clothing that then gets pulled and stretched as the elevator rises or descends.

Today was Jonathon's turn to experience the wrath of the elevator.

We live in an apartment building with an 2 elevator lobbies on each floor. Three elevators in one, four in the other. Our regular set has the four. The kids find it quite fun to run down the hall, press the button, then squish against one of the corners of an elevator, each kid getting their own elevator to "hide" next to.
We've always said not to, primarily because if a door opens we don't want a child there blocking the doorway should someone want to exit. Today though, it was drilled hard into their heads why they should stay far away from elevator doors, period.
The kids, as usual, ran ahead as the adults followed for a walk to the bookstore and surrounding stores. Each kid had squeezed up to an elevator hiding, but when the doors behind Jonathon opened, he didn't move. In fact, he started screaming (as did his sisters) and his -arm- was stuck between the door and the wall it was sliding into to open. I tried to pull his arm and when it became perfectly clear the doors were still trying to open and his arm was not going to move, I tried to push the doors open, realized I was going the wrong way then tried to push them shut. I couldn't understand why they wouldn't close, but they just wouldn't close and let his arm go. The girls were screaming more, and I learned after that Nicholas thought he was helping by pushing the elevator button. Ian jumped in an tried to push the doors open, I yelled that they had to shut to release Jonathon and he successfully pulled them shut. Jonathon's arm came free and amidst much shhhing and crying (still from the girls with Jonathon) we determined that he hadn't broken any bones, he could bend his arm and his fingers moved fine. He didn't even have a scratch.
What he does have is a 3-4 inch long and 1 inch wide section of skin and muscle that has been badly pinched. We applied ice and gave motrin, and he was laughing a few minutes later. In fact, aside from some swelling on his upper arm and a pale blue bruise, it's hardly noticeable. I imagine it will ache tomorrow and probably bruise pretty well after, but considering what could have happened, he was extremely fortunate. And so were we.