The accident took place on Sunday, while Leno was working on a 1907 White Steam Car in his Los Angeles garage. A fuel leak and simultaneous spark caused the freak fire to start.
Leno is famous for his love of cars — his collection boasts over 180 cars, from exotic cars to museum-grade artifacts.
The former talk show host is currently in a burn center in Los Angeles, where he is expected to remain for the next five to ten days.