PITTSBURGH — A 2-year-old boy visiting the Pittsburgh Zoo was killed Sunday when he fell off a railing, which his mother had put him on top of to view a pack of African painted dogs. The animals pounced on the child and mauled him, police said.

It was not clear whether the boy died from the 11-foot fall into the wild dog exhibit area or from the attack, said Barbara Baker, president and chief executive of the Pittsburgh Zoo & PPG Aquarium.