A Pair of Detentions Following London Heathrow Irritant Spray Attack

An additional two individuals are now in custody in connection with a theft at London's Heathrow Airport where 21 people were injured by what is thought to be an irritant spray, according to law enforcement.

A man, 24, was arrested in the Lambeth area for suspected robbery and assault and a 23-year-old woman was arrested on suspicion of conspiracy to commit robbery. They both are still being held, authorities confirmed.

The arrests come after an investigation into an assault at the multi-level parking garage at Heathrow's Terminal 3 on Sunday. Before the attack, a pair of female travelers had stolen from them their luggage upon exiting a parking garage elevator.

A three-year-old girl was one of the injured during the incident. Five people were taken to the hospital for treatment and have since been discharged.

Officers detained a man in his thirties on suspicion of robbery and assault near the scene. He was subsequently released under investigation while inquiries continue.

Police were alerted at about 08:10 GMT after reports came in regarding several people injured by a noxious substance thought to be pepper spray.

The attack - an event that police said was a standalone incident and not considered terrorism - resulted in train delays and the temporary shutdown of the main airport tunnel and the Terminal 3 car park for a short time.