Transcript for 18-year-old survives fiery crash

All his family is just incredibly grateful that he is alive he's got some serious injuries but they say he is showing progress every day. It's miracle. It is hard to believe anyone could have survived this unbelievable crash. But somehow eighteen year old Sam would chance emerged badly injured but alive. Seeing the video. Was incredibly. Shocking. And I'm glad I sorry after airing knew that he was. Well Sam's parents are now at his side as he's treated at Mass. General thankful to the driver and his son. Who were driving behind Sam on route one a one in Dublin New Hampshire last Tuesday. They are dash camera captured the horrifying crash and Dave then jumped out to save Sam. Choose. Jake you know that risk of evening getting hurt themselves. To remove another human life. Out of a situation. Which was dire I'm very very grateful. Sam's now recovering with a traumatic brain injury burns and cuts. It's still not clear why his Jeep crossed over the center line and he drove to Keene state to start his second semester at school. But his parents and his sister are so thankful he's improving every day. Her last name can stay sanskrit. We're. So maybe I can read. Greatly. Sam certainly is getting another chance he continues to receive treatment here at MGH but his family says his future really does look promising. In Boston John Atwater WCVB news five.

This transcript has been automatically generated and may not be 100% accurate.