Heathrow Airport Incident: Hazardous Materials Scare

An incident involving potentially hazardous materials caused disruption at Heathrow Airport in London. The London Fire Brigade was called at 17:01 (UK time) and dispatched crews from Feltham, Heathrow, and Wembley stations.
Part of the airport has been evacuated as a precaution, and the incident is reportedly affecting Terminal 4. Police and ambulances are also at the scene.
National Rail has announced that trains are not stopping at Heathrow Airport Terminal 4 due to the emergency services' response.