An additional two individuals are now in custody in connection with a theft at Heathrow Airport in which 21 people were injured by a substance believed to be pepper spray, according to law enforcement.
A man, 24, was arrested in the Lambeth area for suspected theft and assault and a 23-year-old woman was detained for suspected conspiracy to commit robbery. Both individuals are still being held, the force said.
The arrests come after a probe into an attack at the multi-level parking garage at Terminal 3 on Sunday. Prior to the attack, a pair of female travelers had stolen from them their suitcases after getting out of a parking garage elevator.
A toddler aged three was one of the injured during the incident. Five people went to hospital for treatment and were later discharged.
Police detained a 31-year-old man for suspected robbery and assault close to the scene. He has since been released pending further inquiries while inquiries continue.
Authorities were alerted at approximately 08:10 GMT following reports of a number of people injured by a noxious substance believed to be an irritant spray.
The attack - an event that authorities stated was a standalone incident and not being treated as an act of terror - resulted in train delays and the partial closure of the Central Terminal Area tunnel and the Terminal 3 parking facility briefly.