According to firefighters, the man crashed his full-size sedan into a tree, causing it to overturn and burst into flames near Balboa and Foothill boulevards around 11:54 p.m.
Adam Simpson was working nearby and raced to the scene after he heard a boom and saw smoke.
"I came around here really quick and I saw the guy rolling on the ground on fire, engulfed," said Simpson. "So I pulled off his pants because they were completely engulfed, and put them out basically. And then the fire department got here and they ended up putting the fire out."
The victim was the only one in the car. He was rushed to Providence Holy Cross Medical Center in critical condition with second and third degree burns.