Heathrow Airport's Terminal 4 has been evacuated due to concerns over a possible hazardous materials incident. Emergency services, including teams from the London Fire Brigade and the Metropolitan Police, are currently on the scene assessing the situation.

A spokesperson for Heathrow confirmed that check-in at Terminal 4 has been closed and urged passengers not to travel to the terminal. They stated, "We are asking passengers not to travel to Terminal 4 and supporting those on site. All other terminals are operating as normal. We will provide further information as soon as we can."

Footage shared on social media shows hundreds of passengers with luggage waiting outside the terminal. National Rail has announced that trains are unable to stop at Terminal 4 due to the ongoing emergency response.

Specialist crews equipped with hazmat suits have been deployed to evaluate the situation inside the terminal. A spokesperson for the London Fire Brigade noted, "Firefighters are responding to a possible hazardous materials incident at Heathrow Airport. Specialist crews have been deployed to carry out an assessment of the scene, and part of the airport has been evacuated as a precaution."

As the situation develops, authorities are working to ensure the safety of all passengers and staff. Further updates will be provided as more information becomes available.