Since then, the 19-year-old has been recovering at the Grossman Burn Center at West Hills Hospital.
When Thomas entered the center, he had a one percent chance of survival. After 11 months and over 70 procedures, he was able to walk out of the center on Tuesday.
"I knew this day would come," said Thomas. "But I didn't know when or what to expect of it."
"We have many, many fascinating, wonderful, courageous individuals," said Grossman Burn Center Director Peter Grossman. "But Derek Thomas stands at the very apex."
Thomas was voted "class heartthrob" at Cathedral Catholic High School in San Diego last year. He was a football star, headed to Occidental College to play.
And he was deeply in love with his girlfriend of four years Amanda Post.
The two were coming home from a track trip to Mammoth Aug. 9 along with two friends, when for some reason their car swerved and flipped near Bishop, crushing a bus of Cal Baptist University track students. The bus caught on fire, injuring 15 people.
Cal Baptist's coach Wendy Rice was killed, as was Post and her friend Natalie Nield. Thomas was rushed to the Grossman Burn Center with burns on 85 percent of his body.
"It was the most difficult thing I ever went through," said Derek's father Randy Thomas. "To try and touch on a reality that is unfathomable."
Doctors performed 33 skin grafts, and a hyberbaric oxygen chamber helped rebuild his skin. Thomas struggled to walk again, but eventually the football star heard the cheers once again.
Now the family is whole once again and Thomas has a new goal in life.
"I want to be a doctor," said Thomas. "I'm not really sure what kind yet, but I want to go the pre-med path."
Thomas still has plenty of reconstructive surgeries before becoming a doctor. But he says his immediate priority when he gets to his Encinitas home is to eat San Diego Mexican food.