RALEIGH, N.C. -- A pit bull mauled to death a 6-year-old boy who apparently had climbed over a 4-foot chain link fence to get into a neighbour's yard in western North Carolina, authorities said Wednesday.

The Henderson County sheriff's office was called to a residence in Hendersonville, south of Asheville, on Tuesday and found the boy lying unresponsive in the fenced backyard. The 1-year-old male pit bull was so aggressive officers had to shoot and kill the animal so emergency workers could get to the child, said sheriff's office spokesman Major Frank Stout.

Resuscitation efforts were unsuccessful, and the boy died at the scene from wounds to the head and neck, Stout said. Authorities have not released his name.

"The child appeared to have died a very violent and quick death," Stout said.

The boy's mother called 911 at 4:17 p.m. Tuesday and told the dispatcher she had gone to the bathroom and lost sight of the boy for five to 10 minutes, then was unable to get into the neighbour's yard where he had been attacked.

"I was in the house and I heard the back door shut and I come running and I see him lying in the neighbour's yard," the mother told the dispatcher, according to the 911 recording of the conversation.

Weeping, she said there was blood on the boy's face and he didn't appear to be breathing. He did not respond when she called his name and the neighbours were not home, she said.

After Animal Enforcement officers shot the dog, officers had to push down the chain link fence to access the victim, Stout said.

The mother told 911 that her son and other children climbed over the fence routinely and had played with the dog in the past.

The neighbours adopted the dog from a humane animal shelter about three weeks ago, Stout said. The sheriff's office is currently investigating the unnamed shelter and the dog's history to discover if the animal has ever been deemed dangerous.