"Their body temperature starts going up. It's a massive effect. It gets to the point, where their natural cooling isn't able to overcome the heat of the environment, " said Dr. Neil Reinhardt, an Emergency Room Physician at Tampa General Hospital.

Firefighters with Tampa Fire Rescue say they average a call a week to rescue a child in a car.  Most of the time, it's an accident. A parent may have locked their keys along with their child, in the vehicle.

But it doesn't matter if it's an accident or not.  Time is not on their side.

"It doesn't take long for a child to go into heat exhaustion and heat stroke.  Then they go into seizures. Then they die," Capt. Jace Kohan explained.

It doesn't take long for the heat to set in, and the effects can last a lifetime.