An additional two individuals are now in custody in connection with a robbery at Heathrow Airport where 21 people sustained injuries by a substance believed to be pepper spray, according to law enforcement.
A man, 24, was taken into custody in the Lambeth area on suspicion of theft and assault and a woman, 23 was arrested for suspected conspiring to commit a robbery. They both remain in custody, the force said.
The arrests follow a probe into an assault at the multi-level parking garage at Heathrow's Terminal 3 on Sunday. Before the attack, two women were robbed of their suitcases upon exiting a parking garage elevator.
A three-year-old girl was among the those hurt during the incident. A total of five individuals went to hospital for medical care and were later discharged.
Police detained a 31-year-old man on suspicion of theft and assault close to the scene. He has since been released under investigation while inquiries continue.
Police were called at approximately 8:10 in the morning GMT after reports came in regarding several people injured by an irritating chemical thought to be an irritant spray.
The attack - which police said was a standalone incident and not considered terrorism - caused train delays and the partial closure of the Central Terminal Area tunnel and the T3 car park for a short time.