A British Airways flight from London to Spain was evacuated after smoke filled the cabin moments before the flight was due to land, CNN reports.
Passengers said that the incident -- which occurred on Monday -- was "terrifying" and felt like a "horror film", with travelers shouting that they were unable to breathe.
British Airways confirmed a "technical issue" on flight BA422, which was traveling from London Heathrow to Valencia on Monday afternoon, and said passengers were evacuated from the aircraft.
One traveler on board, Lucy Brown, told CNN that the smoke had been thick with a metallic, chemical odour, adding: "We covered our mouths with our clothes. We don't know why oxygen masks didn't deploy."
"Passengers started shouting they couldn't breathe," she said.
"Flight BA422 from Heathrow to Valencia experienced a technical issue on its landing approach into Valencia. All our customers were evacuated safely by our crew and met by the airport's emergency services," a BA spokesman told CNN in a statement.
There were 175 passengers on board the flight. A spokesman confirmed to CNN that three customers were taken to hospital following the incident "as a precaution", and have since been discharged.