I think there are alot of misconceptions regrading gorilla behaviour. Gorilla's are by nature extremelly teritorial and will protect themselves with force if they feel threatened. When he broke free of his enclosure and was faced with 20 or so people looking at him he perceived all of them as threats. Most likely people began to scream, run away, yell, cry, ect you know the natural human way to react to something they do not understand, or fear. These loud noises and lots of frantic movement would have freaked the gorrila out, and emediatly put him on the defensive.
Had everyone relaxed and not freaked out, odds are he would have gone into an aggresive display of charging, cheast beating, and vocalizations, showing his teeth, nothing to serious.
I do not mean to put the blame on the people observing the situation, as it is not thier fault that the gorilla got out, but i think what the gorilla did was a perfectly natural reaction to being in a threatening situation. The blame for the situation must squarely be placed on the Dallas Zoo.
As for the cops shooting the gorilla, well i wasn't there so i cant say if it was warrented or not. Apparently the Zoo keepers were on their way to get tranqs to take it down, but if the gorilla was chomping on a kids head then id have to say they did what was necessary.
Reports say that the kids were teasing him and this would have prevoked agressive behavior on the gorillas part. I think that this is a lesson learned in that we need to show the respect that these 300lbs animals deserve. To many times have i seen kids at the zoo throwing things into enclosures or pushing sticks into cages right infront of their parents and them saying nothing to them, ive approached several of them asking them to stop, explaining that they are bothering the animals. The Toronto Zoo lost an Orangutan to people throwing oreo's into the enclosure 5-10 years ago.