Emergency services evacuated Heathrow Airport’s Terminal 4 check-in area Monday evening after reports of a possible hazardous materials incident, prompting officials to advise passengers not to travel to the terminal.
The London Fire Brigade said specialist crews were deployed to assess the scene and that part of the airport was cleared as a precaution.
National Rail said trains were unable to stop at the terminal, located southwest of London.
"Please do not travel to Terminal 4, colleagues are supporting passengers on site," said the operator of the U.K.'s main international airport, one of the world's busiest air hubs, located southwest of London.
Heathrow, one of the world’s busiest international hubs, said all other terminals were operating normally.
