Key Facts

• Heathrow Terminal 4 was evacuated while emergency services checked for hazardous materials.
• No dangerous substances were found after a thorough investigation.
• The evacuation involved fire crews arriving around 5 PM local time.
• The London Fire Brigade and Metropolitan Police worked together at the scene.
• Twenty-one people were looked at by medical staff, with one person going to the hospital.
• The terminal reopened by 8:20 PM, and flights mostly stayed on schedule.
• Heathrow apologized for any disruption caused by the incident.