British Transport Police have released CCTV images of the suspects

Monday 22 May - The British Transport Police reported that 'A number of people were treated at the scene by paramedics for coughing and lack of breath', and that the gas has been tentatively identified as CS — commonly used by law enforcement as a riot control agent — based on their symptoms.

The force added, however, that there are at present 'no further concerns for their health'.

While victims told the BBC that the incident was 'frightening', with passengers in the carriage where the gas was released 'trying to frantically get out', there are at present no statements indicating that the attack was terror-related.

'Enquiries have shown the gas was used during a fight between a group on board the train,' the BTP statement reads.

Officers have urged anyone 'who witnessed the incident, or who knows the identity of the men in the released images' to contact them by text on 61016, or by calling them directly on 0800 40 50 40 and quoting reference 171 of 20/07/19.

Author's comment: Crime in London has been skyrocketing in recent years, and this incident is just the latest of many that have prompted native Londoners to leave the city.