Two more people are now in custody in connection with a theft at London's Heathrow Airport in which 21 people sustained injuries by a substance believed to be pepper spray, according to police.
A man, 24, was arrested in Lambeth on suspicion of theft and assault and a 23-year-old woman was detained on suspicion of conspiring to commit a robbery. Both individuals are still being held, the force said.
The arrests come after a probe into an assault at the multi-storey car park at Heathrow's Terminal 3 this past Sunday. Prior to the attack, a pair of female travelers were robbed of their luggage upon exiting a parking garage elevator.
A toddler aged three was one of the injured during the incident. Five people went to hospital for medical care and have since been released.
Officers arrested a 31-year-old man on suspicion of theft and assault near the scene. He has since been released under investigation as the investigation proceeds.
Police were alerted at approximately 08:10 GMT after reports came in regarding a number of individuals hurt by a noxious substance believed to be pepper spray.
The attack - which authorities stated was isolated and not considered an act of terror - caused delays to rail services and the partial closure of the main airport tunnel and the Terminal 3 car park briefly.
