A flight containing US first lady Melania Trump was forced to turn back when the cabin started filling with smoke.
The plane was travelling from Washington to Philadelphia when passengers on board saw smoke and smelt burning.
According to TV reporters travelling with Mrs Trump, smoke filled the cabin 10 minutes into the flight, prompting Secret Service agents to rush to the front of the plane.
Some said they were given wet towels to put over their faces as the dramatic incident unfolded.
It is not immediately clear what caused the problem.
The plane immediately aborted its journey and returned to Joint Andrews Air Force Base in Washington.
Mrs Trump’s spokeswoman, Stephanie Grisham, said "everyone is fine and everyone is safe".
She added the first lady's team was "evaluating" whether to make other arrangements to travel to a scheduled visit to Philadelphia.
The first lady was due to visit a hospital in the city and meet with families of children affected by exposure to opioids while in the womb.
