The mother of a 6-year-old boy who was struck by the family's car recounted a harrowing story of the accident in hopes other parents will be more vigilant.Rachel Kemp is relieved that her son, Nathaniel, is improving at Methodist Hospital. Kemp and her fiancée were picking up the boy and his sister from school at Central Elementary when the accident happened."I turned around to see that they both climbed into the vehicle and was buckled up," Kemp said.Kemp said she heard the door shut and thought everyone was inside, telling her fiancée, who was driving the car, to go.But Nathaniel wasn't in the car."His backpack got stuck, and it caused his car seat to move," she said. "He climbed back out to fix his car seat. He's never done that. Why this time, and why this time did I not check?"Nathaniel suffered broken bones and injuries to his head."Every time I close my eyes, I keep seeing my baby go under that tire, and then I remember seeing my baby laying there lifelessly, and that's just not something I'll ever get out of my head," Kemp said.Kemp decided to tell her story in hopes that other parents will pay more attention."Make sure they're buckled, and make sure your doors are shut before you pull away. Make sure your babies are in there, because all it takes is the split second and you don't know if your baby's ever coming home again," she said.Kemp hopes Nathaniel will be released from the hospital in a few days. She said she will always double-check the mirrors from now on.The school system brought in counselors Thursday for children who witnessed the accident.