Well, I do understand the lethal option being on the table, but I don't understand why the two step solution being presented in the thread few times already wasn't used. I'm talking about the option of tranquilizing the gorilla first and have a guy with a normal gun on standby. They themselves said the gorilla may have acted unpredictably after the tranq shot. Gorillas aren't super fast, let alone faster than bullet, so unless the gorilla in question was the Flash (scratch that, Zoom, obviously the kid was the Flash and there was nothing the parents could have done about him running into the enclosure ) the bullet should have been faster. Though I suppose the zoo staff didn't trust their reaction time to make the judgment call in case the gorilla got angry after getting hit by the dart.