Emergency services were called to reports of an incident at the airport at around 5pm yesterday (September 8).
In a post on X, the airport advised passengers not to travel to the terminal as the incident was being dealt with.
Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a search of the area.
Following the search, Met officers located a cannister of what is believed to be CS spray.
It is thought that this substance caused a reaction to those within the airport.
Around 20 people reported to paramedics after the suspected CS spray caused irritation.
It has been since confirmed that the spray did not cause any life-changing/threatening injuries.
A 57-year-old man was arrested on suspicion of possession of a firearm (CS spray) and causing a public nuisance.
He remains in police custody.
The incident is not being treated as terrorism related.
The investigation remains on-going.
This is a breaking news story. More to follow.
