An additional two individuals are now in custody in connection with a robbery at Heathrow Airport where 21 people sustained injuries by what is thought to be an irritant spray, according to police.
A 24-year-old man, was arrested in Lambeth for suspected theft and assault and a woman, 23 was detained on suspicion of conspiracy to commit robbery. Both individuals are still being held, the force said.
The arrests come after an investigation into an attack at the multi-storey car park at Heathrow's Terminal 3 this past Sunday. Before the attack, two women had stolen from them their suitcases after getting out of a car park lift.
A toddler aged three was among the injured in the event. Five people went to hospital for medical care and have since been released.
Police arrested a 31-year-old man on suspicion of robbery and assault close to the location. He was subsequently released under investigation as the investigation proceeds.
Authorities were called at about 08:10 GMT following reports of several people injured by a noxious substance believed to be pepper spray.
The attack - which authorities stated was isolated and not being treated as terrorism - caused train delays and the partial closure of the main airport tunnel and the T3 parking facility for a short time.
