A security guard closes the gate at the Pittsburgh Zoo, where officials say a young boy was killed after he fell into the exhibit that was home to a pack of African painted dogs, which pounced on the child and mauled him on Sunday, Nov. 4, 2012. (AP Photo/John Heller)

Photo by: John Heller

A security guard closes the gate at the Pittsburgh Zoo, where officials say a young boy was killed after he fell into the exhibit that was home to a pack of African painted dogs, which pounced on the child and mauled him on Sunday, Nov. 4, 2012. (AP Photo/John Heller)