Jay Leno Explains Moment He Got Third-Degree Burns in Car Fire

Jay Leno is breaking down the car fire that sent him to a burn unit with second- and third-degree burns ... and he's pretty cool when talking about the fiery episode.

The comedian sat down for an interview with NBC News' Hoda Kotb and told her how some mechanical work on one of his vintage cars turned ugly in the blink of an eye.

Jay says he was in his Burbank garage last month working on a 1907 White Steam Car, trying to unclog a fuel line. He says he told his friend, Dave Killackey, to blow some air through the fuel line when suddenly he was hit with a face full of gas ... and it only got worse from there.

Jay says his face caught fire when the car's pilot light ignited the fuel ... and he yelled to his friend, "I'm on fire."

Fortunately, Jay says Dave was Johnny on the spot ... pulling him out of harm's way and jumping on top of him to smother the fire.

Jay's back to business as usual already ... he's pretty casual in recalling the scary situation ... which jives with how he's been since the accident, like when he went back to the same garage just 10 days after the incident and was cracking jokes to photogs.

The "Jay Leno's Garage" host canceled some gigs while he was in the hospital but when he was released from the burn center he went right back to what he does best ... making folks laugh, even at his own expense, returning to his weekly Sunday night gig in Hermosa Beach.