Overview
- London Fire Brigade says specialized units were deployed to evaluate a reported hazardous materials issue at the terminal.
- Heathrow closed check-in and evacuated Terminal 4, asking passengers not to travel there and assisting those already on site.
- National Rail reports that no trains are currently calling at Terminal 4 as the emergency response continues.
- Ambulances and other emergency services are present outside the terminal during the ongoing assessment.
- Officials have not disclosed the nature of the incident, and the situation remains developing as operations continue at other terminals.