A building engineer at the Las Vegas hotel where Stephen Paddock was holed up during his massacre last week described being pinned down in a hallway after the gunman opened fire on him from behind the door of his hotel suite shooting perch.

Stephen Schuck was one of the first people to encounter Paddock when he went to check out a faulty fire exit door on the 32nd floor of the Mandalay Bay and Casino on Oct. 1, according to a new timeline of events.

“I was about a third of the way down the hallway and I started to hear shots go off,” he told TODAY in an exclusive interview Wednesday.

Schuck then saw hotel security guard, Jesus Campos, stick out his head from a doorway.

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“He yelled at me to take cover, and as soon as I started to go to a door to my left, the rounds started coming down the hallway," Shuck said. "I could feel them pass right behind my head. Something hit me in the back and I took cover."

“I tried to think, how I could get to Jesus because I could that see he was shot in the leg, and I just told myself, wait for him, he’s going to have to stop shooting some time. It was kind of relentless.”

Schuck calmly called for police over his radio. The gunman eventually turned his attention to the country festival taking place below him outside.

Paddock killed at least 58 people and injuring nearly 500 others in the deadliest mass shooting in American history. He eventually killed himself before authorities reached his room, police said.

Schuck said he feels “incredibly blessed” that he came out of the shooting alive and unharmed.

He and his family credit Campos for saving his life by warning him about the gunfire.

“If he yelled a second too late, I would have been shot. So I owe him my life," he said.

Despite the traumatic event, Schuck said he plans to return to work at the hotel.

“It’s definitely difficult, but for someone to do something so cowardly and despicable, I’m not going to let that change my life,” he said. “I want to go back to work. I like my career and I’m not going to let that define me.”

EDITOR'S NOTE: An earlier version of the video within this story was headlined incorrectly, stating that the shooter warned Stephen Schuck of the danger. In fact it was hotel security guard Jesus Campos who warned him. The headline has been changed. TODAY regrets the error.