Two investigators from the National Transportation Safety Board were already at work Friday to look into the fire that appeared after American Airlines flight 1006 arrived in Denver the evening before.

Dozens of passengers were forced to stand on the wing of an American Airlines plane at Denver International Airport as they evacuated the aircraft after one of its engines caught fire Thursday evening.

An American Airlines flight from Colorado Springs to Dallas diverted to Denver after the FAA says the crew reported “engine vibrations.” Soon after landing, the engine caught on fire. In a harrowing scene,