PITTSBURGH – A 2-year-old boy who fell into an exhibit of African wild dogs was killed by the animals, not the fall, the president of the Pittsburgh Zoo said Monday, adding a horrific coda to a tragedy that has devastated staff and shocked patrons.

The boy’s mother had picked him up and put him on top of a railing at the edge of a viewing deck late Sunday morning when he lost his balance and fell, said Barbara Baker, CEO and president of the Pittsburgh Zoo and PPG Aquarium.

There was a safety net below the railing, but it failed to catch him and the boy dropped more than 10 feet into the enclosure, she said.