The United flight #UA5869 took off from Aspen at 1:45 pm local and landed at 2:20 pm at Denver International Airport. Shaken holidaymakers could be seen fleeing the aircraft blaze on foot after the left engine of the Bombardier CRJ-701E caught fire. Images from the scene show orange flames erupting from inside a blackened engine behind the left wing. Fire also rages on the runway beneath the aircraft as flames lick what appears to be spilled jet fuel. Denver Airport tweeted: "Arriving SkyWest flight 5869 was reported on fire, all passengers evacuated safely with no injuries. Denver Fire is on scene assessing." "All runways are now open as investigation into SkyWest fire continues," tweeted the Airport half an hour later. "Other airport operations remain unaffected," the tweet added. The cause of the fire is not yet known.