Pittsburgh Zoo officials and police were trying to determine what happened after a 2-year-old boy fell into an African painted dog exhibit on Sunday and died before police could save him.
A news conference was scheduled for 10 a.m. Pacific Standard Time on Monday.
Police said the boy's unidentified 34-year-old mother, from Pleasant Hills, Pa., was holding her son over a four-foot railing in an elevated viewing area when he fell. The boy hit and then flipped over a mesh barrier before hitting the ground.
Several of the dogs immediately attacked, and one had to be shot by a police officer. Witnesses estimated the whole event lasted about five minutes, police said.
It's not known if the boy died on impact or if the animals killed him.
Steve Feldman, a spokesman for the Assn. of Zoos and Aquariums, told the Associated Press that it might be the first reported death of a child at an accredited zoo in 40 years.
It was the zoo's first visitor death.
Both police and the zoo have launched investigations into the incident.
The boy's father arrived at the scene after the fall, police said. The mother and the father are receiving grief counseling, according to the Associated Press.
After Sandy, hot meals and help at Hoboken Elks Club
Twitter in the time of Sandy: A few lies, and then redemption
Sandy spared Macy's Thanksgiving parade giant balloons, floats