just got around to watching the video, my passive observations
the gorilla seemed to be dragging the kid around like a toy
it wasn't outright physically harming the child
it looked like it sat the boy up and checked its butt or something
it looked to be getting aggrevated by the crowd
with how ultra strong these things are, it could break the kids arms / legs / neck without much effort at all, not even meaning to it could of. It is an animal that isn't used to handling fragile human children, it is more used to much stronger ape children ( if it had been a parent up to this point anyway ) so who knows
in the end i dont think the Gorilla would have PURPOSEFULLY hurt the kid. Accidently? Very likely, especially with how it was dragging the kid around.
As some have stated, trying to shoot Tranq's at it would not have done the job instantely and in the time period between getting shot and going down, it could of done serious harm to the kid once aggrevated. If the thing was in full on defense mode, someone jumping into the area at this point would have been a really dumb move. Could of easily gotten killed.
Not sure what other options were available to the Zoo at this point. Tragic event no doubt. Thankfully one that does not occur often