An additional two individuals are now in custody in connection with a theft at Heathrow Airport where 21 people were injured by a substance believed to be an irritant spray, according to law enforcement.
A 24-year-old man, was arrested in the Lambeth area on suspicion of theft and assault and a woman, 23 was detained on suspicion of conspiring to commit a robbery. They both are still being held, the force said.
The arrests come after a probe into an assault at the multi-level parking garage at Terminal 3 on Sunday. Before the attack, a pair of female travelers were robbed of their suitcases upon exiting a parking garage elevator.
A three-year-old girl was among the those hurt during the incident. Five people were taken to the hospital for treatment and were later discharged.
Officers detained a 31-year-old man on suspicion of robbery and assault close to the location. He was subsequently released under investigation while inquiries continue.
Police were alerted at about 08:10 GMT after reports came in regarding a number of people hurt by an irritating chemical thought to be pepper spray.
The assault - an event that police said was isolated and not being treated as terrorism - caused train delays and the temporary shutdown of the main airport tunnel and the T3 parking facility briefly.
