A security guard closes the gate at the Pittsburgh Zoo, where a 2-year-old boy was killed Sunday. John Heller/AP hide caption itoggle caption John Heller/AP The Two-Way Boy Killed In Dog Exhibit At Zoo: Onlookers' Screams 'Just Kept Coming' November 5, 2012 In Pittsburgh, the 2-year-old's mother lifted him on to a railing. Tragically, he fell into the animals' exhibit and was set upon by the pack. Zookeepers were eventually able to lure most of the 11 dogs away. One had to be shot by police.