Jesus Campos, a security guard at the Mandalay Bay Resort and Casino, appeared on "The Ellen DeGeneres Show" in an episode set to air Wednesday, publicly telling his story in detail for the first time.

He was hailed as a hero for his actions during the Las Vegas shooting, but disappeared for days after authorities changed key details in the timeline of the massacre.

Jesus Campos, the security guard injured in the Las Vegas shooting who was lauded by authorities as an "absolute hero" for his efforts assisting police officers, appeared on "The Ellen DeGeneres Show" on Tuesday after disappearing for days.

For the first time, Campos publicly gave key details of his experience at the Mandalay Bay Resort and Casino on October 1, when Stephen Paddock opened fire from the 32nd floor on thousands of concertgoers across the street, leaving 58 people dead and hundreds more wounded. The episode is set to air Wednesday afternoon.

Campos had fallen off the radar of union leaders, backed out of media interviews, and sparked concern from neighbors who said they had no idea where he was amid a wide-ranging investigation into the shooting that has so far yielded more questions than answers and prompted a proliferation of conspiracy theories.

A security vehicle blocked an entrance to the Mandalay Bay on October 4 in Las Vegas. Getty Images/David Becker

As he told DeGeneres, in clips provided to the Las Vegas Review-Journal, Campos arrived on the 32nd floor that Sunday night to investigate a door that was left open. He called engineering to help him fix the door, he said, when he heard drilling sounds. A heavy door slammed, which is what Campos said he thought caught Paddock's attention.

"I heard rapid fire, and at first I took cover," he said. "I felt a burning sensation. I went to go lift my pant leg up and I saw the blood. That's when I called it in on my radio that shots had been fired, and I was going to say that I was hit, but I got on my cellphone just to clear radio traffic so they could coordinate the rest of the call."

That's when a maintenance worker named Stephen Schuck arrived from a higher floor, with no knowledge that the gunman was nearby. Schuck recalled walking down the hallway and seeing Campos before hearing shooting that sounded like a jackhammer. Campos told him to get down.

"Within milliseconds, if he didn't say that, I would have been hit," Schuck said, adding that he could feel the pressure of the bullets going past him.

A woman came out of a nearby room, and Campos told her to go back inside.

"Really, he saved your life, and he saved also the woman who came out of the door to go into the hallway," DeGeneres said.

She said that Campos didn't want to rehash the experience but that she wanted him on the show so he could share his story and so DeGeneres and her viewers could "celebrate him." Campos then thanked the first responders, police officers, the FBI, the community, and hospital workers who came together that night, "even in the darkest hour."

Schuck added: "Definitely, I'd want to thank the first responders, and people on the ground at the show helping each other out. I think the acts of humanity were major that night. And I want to thank Jesus again, from my family and all my friends and everybody, for saving my life."

Investigators have still not determined a motive for Paddock's deadly rampage, and Las Vegas authorities have changed their version of the shooting's timeline multiple times.

Campos was shot in the leg as he approached the door of Paddock's hotel suite on the 32nd floor, and officials said he was "absolutely critical" to the police response to the shooting by notifying his dispatch immediately and advising officers as they arrived.

But Campos disappeared Thursday before he was supposed to appear for several TV interviews, prompting the Las Vegas police to tamp down conspiracy theories that he was missing or under arrest.

"We tell people what we know," Larry Hadfield, a Las Vegas police officer, told the fact-checking website Snopes. "If they don't believe it but they're going to believe whatever website, then I don't know what else to tell you."