Just before 7pm Monday, parents of Lilly Parsons, 4, reported her missing. They said she'd been playing outside and disappeared.

"They'd done some searching to determine if the child had run to the neighbors', something like that, but after a little searching, the timeframes we're not sure of yet, they called 9-1-1," said Lt. Tim Jones, spokesman for the Johnson County Sheriff's Office.

Neighbors and deputies helped the family search. Neighbors tell The 33 News they worried the young girl may have wandered off and fallen into a pool.

Deputies found Parsons in a black Denali SUV, parked in the driveway of the home, around 9pm.

"Right now, we're treating it as an accident, but we're continuing the investigation to make sure it is an accident. We're not just taking it for granted," said Jones.

The Tarrant County Medical Examiner's is working  to determine how she died. It says she died at 7:20, just a half hour after her parents reported her missing.

Deputies still don't know why she was in the vehicle.

As their investigation continues, the age of the victim hits home.

"It takes a hard toll on the investigators. You know, it doesn't get any easier. Any kind of death's bad, but when it's a child, it's especially bad," said Jones.

The medical examiner's office is waiting on toxicology results before releasing a cause of death. The sheriff's office expects the sun played a major role.

If there's one thing deputies hope can be learned from this tragedy, it's that hot vehicles are not a place to play.