(CNN) -- A group of African painted dogs killed a boy who fell into their exhibit Sunday at the Pittsburgh Zoo.
Barbara Baker, the zoo's president, said the child was around 3 years old.
He "fell off an observation deck that's about 14 feet above the exhibit," she said, "and was killed by the dogs."
"Our emergency teams and our Pittsburgh police responded immediately, but there wasn't anything that could be done," added Baker.
The boy fell into the enclosure at 11:45 a.m., and visitors quickly alerted staff, the zoo said in a statement. A zookeeper moved seven of the 11 dogs out of the exhibit, and a Veterinarian Department member shot darts trying to scare away the remaining dogs.
"Unfortunately, the dogs were in pack mentality and not responding," the zoo said.
Zookeepers, meanwhile, entered the exhibit to try to lure the dogs away, but they could not reach the boy in time. The keepers and Pittsburgh police officers continued efforts, too, to lure away the dogs, and "one aggressive dog was shot and killed by an officer," according to the zoo.
The Pittsburgh Zoo and the associated PPG Aquarium are closed until further notice.
African painted dogs are among the most endangered dog species in the world, with less than 5,000 left in the wild, according to the zoo. The zoo has a breeding program.
Each is about the size of a small German shepherd, Baker said.