A 7-month-old baby boy is dead after he was attacked by a dog while being watched by a family member in Ohio on Sunday, WHIO-TV reported.

Jonathon Quarles Jr. was spending the day with his step-grandmother at her Dayton home when the dog attacked and killed the baby, police told the station. A neighbor called 911 from the scene that afternoon after the relative rushed over with the unresponsive child.

"She just knocked on my door, bangin' on my door. She had a baby in her hand. The baby's not breathing. You need to get here now," the neighbor told the dispatcher, according to the station.

The baby was identified by the Montgomery County Coroner after an autopsy was performed Monday.

Homicide detectives are to investigate Quarles' death. It was not immediately clear what led the dog to attack the child, who was from out of state. Police said the step-grandmother was distraught and needed help to walk.

The type of dog involved was also not confirmed, but according to the county Animal Resource Center, an American Staffordshire terrier is registered at the Riverside Drive address.

American Staffordshire terriers are said to be similar to pit bulls. The same dog at the home was involved in a June 3 incident when the animal attacked another dog being walked by its owner outside the home, WHIO-TV reported.

The owner walking the dog, which suffered leg bites, did not press charges but wanted the attack on record.

Officers from animal control have removed the dog that killed the 7-month-old from the home.