Twenty years after the September 11 attacks, a former American Airlines ticket agent spoke about the guilt he feels for allowing 9/11 terrorists to board flight 77.

Guilt tortured Vaughn Allex for years, and even 20 years later, there are still some things he'd rather not discuss. The former American Airlines ticket agent told ABC News that he blamed himself for allowing two 9/11 terrorists to get onto flight 77 despite being late.

"I blame myself, I thought, you know, if I had done something different, if I'd not let them on, if I just said to the agents, these two guys are late, let them get the next flight," the former ticket agent said.

Over the years, Allex said his friends and colleagues told him that he was only doing his job.

September 11 Attacks: 9/11 Terrorists on American Airlines Flight 77

On September 11, 2001, Vaughn Allex met the two men at Dulles International Airport in Virginia, where he worked as an American Airlines ticket agent.

At the time, the former American Airlines ticket agent recalled that brothers Salem and Nawaf Al-Hazmi, who appeared lost, ran into the terminal and approached his counter.

Allex said the two full-fare, first-class passengers arrived late that day. However, he made sure they made it to flight 77 instead of rebooking them.

The former American Airlines ticket agent has lived with that decision for the past 20 years. He said the check-in of the two brothers was odd. Allex noted that one of the brothers looked "gruff," while the other "was almost dancing, he was moving from foot to foot and grinning and looking around."

At the time, he said his thought was it was the guy's first time on an airplane, and he was just excited. Allex said the guy was totally unresponsive despite being asked to read. He said the guy only "smiled and danced and was oblivious to what was going on."

"That's the image I have, is the two of them standing there and the one just dancing, it was the oddest thing," he noted.

Allex said he marked the men's tickets for additional security after they could not answer basic security check-in questions.

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Former American Airlines Ticket Agent Vaughn Allex Deals With Another Guilt

Twenty-four hours before the check-in of the alleged 9/11 terrorists, Vaughn Allex's longtime co-worker and close friend MJ Booth asked him for advice about her possible flights regarding her trip to Las Vegas.

MJ considered taking a flight to Chicago or even Dallas to connect to Las Vegas. However, the former American Airlines agent encouraged her co-worker to take flight 77 to Los Angeles with a connecting flight back to Las Vegas.

Allex, unaware of what would happen hours later, advised his friend that it was a better flight because it was a transcontinental flight with a meal and a movie.

Allex also shared that he started to feel better about his role in the deadly flight after purchasing the 9/11 Commission report.

The report has detailed missteps by government agencies that failed to uncover the plot of the militant Islamist terrorist group Al Qaeda. He said the turning point for him was when the 9/11 Commission had interviewed him.

Allex noted that he also bought a book that contained hundreds and hundreds of pages, and his on page three. The former American Airlines agent said he had "a little paragraph and a footnote, footnote number 12."

Vaughn Allex added that knowing so many other people were also involved set him free of the guilt he has been carrying with him.

"That's when it started to get better. That's when I went - oh my gosh... There were so many other people involved. There were so many innocent people that just touched on this. And I had just such a small, tiny five-minute part of it. But before that, it was terrible," Allex said.

The September 11 attacks, often referred to as 9/11, were a series of four coordinated terrorist attacks by Al-Qaeda against the U.S. on September 11, 2001.

On that morning, four commercial airliners traveling from the northeastern U.S. to California were hijacked by 19 Al-Qaeda terrorists.

The first plane, American Airlines flight 11, was flown into the North Tower of the World Trade Center complex in Lower Manhattan. The World Trade Center's South Tower was hit by the second plane, United Airlines flight 175.

The American Airlines flight 77 was the third plane, and it was deliberately crashed into the Pentagon. It killed 125 people inside the Pentagon and all 64 passengers and crew, including the five hijackers on board the plane.

The last plane, United Airlines flight 93, was flown in the direction of Washington, D.C. The plane crashed into a field near Shanksville, Pennsylvania because its crew and passengers fought back against the hijackers, ultimately diverting the flight from its intended target of either the U.S. Capitol or the White House.

Almost 3,000 people lost their lives during the September 11 attacks.

READ MORE: 2 More People Killed in the 9/11 World Trade Center Attack Identified Days Ahead of 20th Anniversary

This article is owned by Latin Post

Written by: Jess Smith

WATCH: Former Ticket Agent Grapples With Guilt After Allowing Hijackers on 9/11 Flight - From ABC News