Jay Leno Shares the Shocking Details of His Burn Accident: 'My Face Was on Fire'

Just over a month after a terrifying accident in his garage led to severe second-degree burns all over his face and upper body, Jay Leno is opening up for the first time about what really happened that day.

"When you work with cars, you have a lot of accidents," admits the comedian, 72, who spent nine days at the Grossman Burn Center at West Hills Hospital recovering from his injuries and undergoing two skin graft surgeries. "But this is bigger than most."

Nov. 12 began as a normal day as the host of CNBC's Jay Leno's Garage and his longtime friend, Dave Killackey, worked on a clogged fuel line in the undercarriage of a 1907 White Steam Car (seen in the exclusive image above) parked in the TV host's 140,000 square foot Burbank garage.

Matt Sayles

"With a steam car, you have gasoline, but you also have a vaporizer which is heated by a pilot light to turn water into steam," Leno explains.

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Once a little air was pushed into the line in an attempt to unclog it, "I got a face full of gasoline," Leno recalls. "I knew how close I was to the pilot light and I thought 'Uh oh.'"

Matt Sayles

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Instantly, a spark reacted with the gas and the comedian's face was aflame. "It felt exactly like my face was on fire," he says. "Maybe like the most intense sunburn you've ever had, that'd be fair to say."

Despite the shock, Leno knew to shut his eyes and hold his breath as he struggled to get out from underneath the vehicle before Killackey helped pull him out. "I'm not a panicky guy, but I knew if I breathed in I could scorch my lungs," he says. "I was under the car maybe 10 seconds before Dave pulled me out. Any longer than that I could have lost my eye."

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Leno smothered his face into Killackey's work shirt until the flames subsided; within minutes paramedics arrived, and by the next day, Leno had checked into The Grossman Center, treated for burns across his face, neck, chest, hands and left arm.

"When he came in, his burns were deeper than I anticipated," says Dr. Peter Grossman, Leno's surgeon. "Jay is definitely an outlier in terms of how well he's healed considering the severity of his injuries."

Matt Sayles Jay Leno with Dr. Grossman at Grossman Burn Center

Leno declined to take pain medication during at any point. "The pain is a reminder that I'm an idiot!" he insists.

Over nine days, Leno — whose wife of 42 years, Mavis, slept beside him at The Center — underwent two skin grafting surgeries (one with human cadaver skin and another with pig intestine) to help regenerate new healthy skin, as well as sessions in hyperbaric chambers to help oxygenate tissue.

Famous friends reached out in support. "Travolta sent me a big Italian basket, Tom Selleck sent flowers and Russell Crowe called from Australia. I've been in this business a long time and to feel that love was really touching."

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Matt Sayles

Within six days after he left the Center, Leno was back onstage, performing standup at the Comedy & Magic Club in Hermosa Beach, Calif. "It kind of gave my career a shot in the arm because it's like, 'Let's go see him before he burns up again,'" jokes Leno, who also returned to the garage soon after. "It was really fun to be back at work again."

For more on Jay Leno's accident and recovery, pick up the latest issue of PEOPLE, on newsstands Friday.

Now, as Leno continues to heal, he says he's aware that the situation could have been much worse.

"I know how bad it could have been," says Leno. "But I'm okay. And I'm sure I'll continue to do the same stupid things I've always done. Just maybe a little bit more carefully!"