The plane, on route from Denver to Los Angeles International Airport, "reported striking a pedestrian during takeoff at DEN at approximately 11.19pm on Friday," the airport's official X account wrote.
A spokesperson for the airport said the pedestrian, who jumped a perimeter fence, has died.
They said the unidentified person was hit two minutes after entering the airport.
The person is not believed to be an airport employee.
"We're stopping on the runway," the pilot tells the control tower according to the site ATC.com.
"We just hit somebody. We have an engine fire."
The pilot tells the air traffic controller they have "231 souls" on board and that "individual was walking across the runway".
The air traffic controller responds that they are "rolling the trucks now" before the pilot tells the tower they "have smoke in the aircraft. We are going to evacuate on the runway".
Frontier Airlines said in a statement flight 4345 was the one involved in the collision and that "smoke was reported in the cabin and the pilots aborted takeoff".
It was not clear whether the smoke was linked to the crash with the pedestrian.
"The Airbus A321 was carrying 224 passengers and seven crew members," the airline said.
"We are investigating this incident and gathering more information in co-ordination with the airport and other safety authorities."
Passengers then left via slides and the emergency crew bussed them to the terminal.
The airport spokesperson said 12 passengers suffered minor injuries and five were taken to local hospitals.
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