An estimated 200,000 travelers worldwide could be impacted by the closure of London's Heathrow Airport, including many trying to fly into and out of New York City.

Authorities said it wasn't clear what caused the substation fire, but London's Metropolitan Police said there was "currently no indication of foul play." At JFK, people have been stranded all day.

Some 120 flights were in the air when the closure was announced, with some turned around and others diverted to Gatwick Airport outside London, Charles de Gaulle Airport near Paris or Ireland’s ...