a 4-year old boy entered the silverback gorilla enclosure at the Cincinnati zoo last week. the crowd above were screaming. the gorilla carried the boy around in the moat for 10 minutes. some witness said the gorilla was trying to help the boy instead of hurting him. the zoo explain the boy was in danger and the gorilla could have hurt him. the zoo decided to kill the gorilla instead of using tranquilizer because it would take a few minutes for the drug to take effect.