A zoo news release said keepers were able to clear seven of the 11 dogs after the child fell, and darts were shot to scare the dogs away from the child. But "unfortunately, the dogs were in pack mentality and not responding."
"The screams just kept coming and coming: 'Someone help. Someone has to do something,'" Angela Cinti, 20, of Bethel Park, Pa., told the Pittsburgh Post-Gazette.
The newspaper said the tragedy occurred shortly before noon at the Highland Park complex, and the zoo was shut down within a half-hour. The report said the zoo will stay closed indefinitely.
A Pittsburgh police officer shot and killed one of the 11 dogs in the exhibit who refused to leave the child's body, the newspaper said..
Zoo President and Chief Executive Officer Barbara Baker said the child was with his mother when he fell over a wooden railing and off of a mesh barrier. A zoo spokeswoman told the newspaper the railing is 4 feet high and the barrier is 14 feet above the open exhibit space.
The report did not give the name of the child or his mother.
Celebrity Couples of 2014 [PHOTOS]