A Frontier Airlines jet preparing to depart Denver International Airport for Los Angeles struck and killed a pedestrian on the runway Friday night, triggering an engine fire and a chaotic scene later captured in disturbing videos circulating online.

Denver International Airport confirmed that Frontier Flight 4345, bound for Los Angeles International Airport, reported striking a pedestrian at about 11:19 p.m. local time (1:19 a.m. ET Saturday), after which an engine fire broke out and was subsequently extinguished.

According to airport officials, the pedestrian had breached a perimeter fence roughly two minutes before the incident and was pronounced dead at the scene. The person has not been publicly identified and is not believed to have been an airport employee.

On Sunday, airport CEO Phil Washington sought to reassure the public, saying, “Safety is paramount in everything we do in aviation and at DEN,” adding that investigators continue to gather information.

“We know there are questions to be answered still,” he added.

Video a passenger posted to social media appears to capture the moment of impact during takeoff. A loud crashing sound can be heard, followed by screams from passengers on the plane.

Nikil Thalanki, a passenger, told NBC affiliate KUSA of Denver that the fire broke out shortly after the plane’s wheels momentarily lifted off the ground before landing.

“Smoke filled the cabin completely — it was super hard to breathe,” he said. “And then we were sitting there, what they told us to wait there, just remain seated for like two, three minutes, maybe four minutes, and then they opened up the exits.”

Fellow passenger Franco Valera told KUSA that he heard a loud noise and then looked out the plane’s window and saw the engine on fire.

“I’m just trying to relax as everyone’s screaming, and people are getting up,” he said. “And it was a little scary.”

It is not clear whether the engine fire was related to the collision.

Mohamed Hassan, another passenger, also described the chaotic scene on the plane to KUSA.

“Honestly, it was the scariest experience of my life,” he said. “I was on the flight, and I looked to my right and I just saw a fire, I heard a loud boom, people started screaming.”

“I thought I was going to die,” he added.

Hassan said passengers were stuck on the plane for about three minutes before they were evacuated, during which he inhaled “a lot of toxic fumes.” He said that passengers were screaming and that “emotions were really high at that time.”

Another passenger, Kimberly Randel, said that when the emergency doors opened, people were running to get off the plane.

“They made us leave our stuff, our bags, and we jumped,” he told KUSA. “It was horrific moment, a terrifying moment in my life.”

Karen Moon, who was also on the flight, added that she was just happy she was able to disembark safely.

“Nothing happened to us other than a minor inconvenience,” she said. “We’re alive, and that’s the good thing, right?”

The plane, a narrow-body Airbus A321, was carrying 224 passengers and seven crewmembers, who were evacuated on slides after smoke filled the cabin, the airline said.

“The aircraft reportedly struck a pedestrian on the runway during takeoff. Smoke was reported in the cabin and the pilots aborted takeoff,” the airline said. “We are deeply saddened by this event.”

The Denver airport said 12 people reported minor injuries, including five who were taken to local hospitals.

“We are extremely saddened by this incident and express our sympathies to those involved,” the airport said in a statement.

As they got off the plane using emergency slides, another passenger recorded dimly lit videos appearing to show damaged engine blades.

Emergency crews bused passengers to the terminal, the airport said.

The Federal Aviation Administration confirmed it is investigating the incident.

Transportation Secretary Sean Duffy confirmed the incident Saturday on X, writing that “a trespasser breached airport security at Denver Int’l Airport, deliberately scaled a perimeter fence, and ran out onto a runway.”

“No one should EVER trespass on an airport,” he wrote.

In its statement, the airport said that it had shut Runway 17L and that the National Transportation Safety Board had been notified.

The Association of Flight Attendants-CWA said in a statement that it commended “the quick and professional actions of the pilots and the firefighter first responders who ensured the fire did not spread as everyone onboard was ushered to safety.”

Hassan said he was too shaken up from the incident and declined to take the flight Frontier offered him free to Los Angeles on Saturday morning.

“I’ve never experienced something like that,” he told KUSA.

The CEO of Denver International Airport, Phil Washington, said in a statement Sunday that the airport continues to gather information.

“We know there are questions to be answered still. As this is an active investigation with numerous other agencies involved, it is going to take some time as we are still confirming what information we can share at this time,” Washington said.

“This was a horrible and preventable tragedy that has affected many due to the actions of one person who apparently trespassed at an airport and lost their life as a result. Safety is paramount in everything we do in aviation and at DEN we want to make sure we have all the facts before information is released,” he concluded.

A spokesperson for the airport stated it will perform an incident analysis. That will include “reviewing the ongoing investigation” and the “perimeter security program.”

Mithil Aggarwal is a Hong Kong-based reporter/producer for NBC News.

Matthew Mulligan is a senior reporter for the NBC News Social Newsgathering team based in London.

I’m a reporter on NBC News’ breaking news team, covering crime, extreme weather, pop culture and more. I recently covered Hurricane Milton, which devastated the Tampa, Florida, metropolitan area, and the student-led protests at Columbia University.

Francie Ebert contributed.