A man has been arrested over the incident on Monday evening that forced Heathrow Terminal 4 to close and evacuate its check-in area.
Emergency services were called to attend a ‘potential hazardous materials incident’ at the airport and the check-in area was closed for almost two hours at about 6.30pm. Around 20 people reported injuries.
Specialist officers conducted a search of the area and found a canister of what is believed to be CS spray, a type of tear gas.
The Metropolitan Police said: “It is thought that this substance caused a reaction to those within the airport.”
A 57-year-old man has been arrested on suspicion of possession of a firearm (CS spray) and causing a public nuisance.
He is currently in police custody. Police said the incident is not being treated as terrorism related.
