A fatal runway intrusion at Denver International Airport led to a deadly collision involving a Frontier Airlines aircraft during its takeoff run, triggering an engine fire and an emergency evacuation of passengers on board.

The Frontier Airlines flight, bound for Los Angeles, reportedly struck a pedestrian on the runway at about 11:19 p.m. on Friday, according to the airport’s official X account. The impact forced an immediate emergency response as the aircraft’s departure was abruptly disrupted.

An airport spokesperson confirmed that the individual had gained access to the airfield by jumping a perimeter fence before entering the active runway. The person was fatally struck by the departing plane. Authorities added an investigation is underway to determine how the security breach occurred and how the individual reached the restricted area.

Runway collision, smoke reported during emergency evacuation

Videos shared on social media by a passenger appear to show the moment of impact as the Frontier Airlines aircraft began its takeoff roll at Denver International Airport. The footage captures a sudden loud crashing noise, immediately followed by visible panic and screams from passengers inside the cabin.

Testimonies from air traffic communications also indicate that the pilot of a Frontier Airlines aircraft declared an emergency after a fatal runway incident at Denver International Airport during takeoff. The crew reported that the plane had struck a person on the runway and that an engine fire had started as a result of the impact.

According to air traffic communications, the crew informed controllers that they had been forced to stop on the runway after the collision and confirmed that there were 231 people on board. The pilot also indicated that an individual had been seen on the runway prior to impact.

Emergency responders were immediately dispatched by air traffic control as the situation developed. The crew further reported smoke inside the aircraft and initiated an evacuation directly on the runway. Frontier Airlines later confirmed that flight 4345 aborted its takeoff after smoke was detected in the cabin, although it was not immediately clear whether the smoke was directly caused by the collision.

Transport Secretary says trespasser deliberately entered runway

Twelve people reported minor injuries following the incident, with five of them requiring transport to local hospitals, according to airport officials. The airport expressed deep sorrow over the event, stating that it is saddened by the incident and extends sympathies to those affected.

US Transportation Secretary Sean Duffy later confirmed that a trespasser had breached airport security by scaling a perimeter fence and running onto an active runway before the fatal collision occurred. “No one should EVER trespass on an airport,” Duffy wrote on X.

The runway involved, 17L, was shut down following the incident and the National Transportation Safety Board was formally notified as part of the ongoing investigation, according to airport officials.

In a separate statement, the Association of Flight Attendants-CWA praised the coordinated response of the Frontier Airlines flight crew and emergency services. The group highlighted the swift and professional actions of the pilots and firefighter first responders, noting that their efforts helped prevent the fire from spreading and ensured that all passengers were safely evacuated from the aircraft.