A three-year-old boy has died after he was found unresponsive inside a parked car outside his family's Florida home on a day when temperatures soared into the mid-90s.

The child's father called 911 at about 10:40pm on Saturday after finding his son inside the vehicle in the driveway of the family home on Emerald Shore Drive in Riverview, a gated community just outside Tampa, according to the Hillsborough County Sheriff's Office.

Deputies rushed to the home and the boy was transported to St. Joseph's Hospital-South, where he was pronounced dead.

The little boy's death is now under investigation, with detectives still trying to establish how long he had been inside the car before he was discovered.

No charges have been filed.

Sheriff Chad Chronister called the death a devastating reminder of how quickly a vehicle can become deadly in Florida's crushing summer heat.

'This tragedy underscores a critical danger that we must never take for granted,' Chronister said in a statement.

'A vehicle can reach lethal temperatures within minutes. We urge every parent and caregiver in our community to make hot vehicle safety a priority. Never leave a child unattended in a vehicle, even for a moment.'

Riverview baked under blistering conditions on Saturday, with the temperature reaching about 95F. With humidity factored in, it felt hotter than 100F.

Even after the sun begins to set, cars can retain dangerous levels of heat, particularly after sitting in direct sunlight during the day.

Authorities have not said whether the boy was accidentally left inside the vehicle, climbed into it himself, or how long he had been in the car before his father found him.

For now, the Hillsborough County Sheriff’s Office said the investigation into the three-year-old’s death remains ongoing. 

The tragedy marks at least the eighth child hot-car death reported in the United States so far this year, according to the national child-safety nonprofit KidsAndCars.org.

The group said at least 37 children died in hot cars nationwide last year.

It was also the second reported child hot-car death in Florida this year, according to Kids and Car Safety. The first happened on March 31 in Winter Haven.

Amber Rollins, executive director of Kids and Car Safety, said the deaths are especially agonizing because, in many cases, the child was loved and cared for by the very person who did not realize they were still in the vehicle.

'As a mom, I cannot imagine losing a child and losing a child in this way. It's just completely devastating,' Rollins told Fox 13.

'Most of the time, it's somebody who loved that child, who was responsible for their death and had no idea it was happening. Just completely heartbroken, really.'

Rollins said the organization’s data shows that children are unknowingly left behind in a vehicle in about half of hot-car deaths.

In roughly one in four cases, she said, a child gets into a vehicle alone and is unable to escape.

She said parents and caregivers should make a habit of checking the back seat every time they get out of a vehicle.

‘Open that back door, check the back seat every single time you leave your vehicle,’ Rollins said.

She also urged families to use reminders, including leaving a stuffed animal in the back seat and moving it to the front when a child is riding in the car.