A three-year-old boy died in Bradley County on Wednesday afternoon and his five-year-old brother was in critical condition.
Authorities first thought the incident was a drowning, but later said it was not.
At approximately 2:45 p.m, Bradley County Emergency Medical Service responded four paramedic ambulances and a paramedic supervisor to what initially was thought to be a drowning of the young brothers.
EMS units arrived at an Armstrong Road location where the two boys were.
The three-year-old was not responsive and CPR was initiated by EMS. The other child was unresponsive as well but did have a pulse.
A medical helicopter was requested to respond to the scene. Life Force's air medical unit responded and landed nearby. The five-year-old was flown to Children's Hospital at Erlanger.
The three-year-old was transported to Sky Ridge Medical Center where he was later pronounced dead.
Officials said, "At this time it has been determined that it was not a drowning. The cause is being investigated by the Bradley County Sheriff's Department and the Bradley County Medical Examiner's Office."
Brent McDonald of NewsChannel 9 said there is no pool or pond at the family home.
He was advised that the mother had driven the boys to her father's house several miles away.