An additional two individuals are now in custody in connection with a theft at London's Heathrow Airport in which 21 people were injured by what is thought to be pepper spray, according to law enforcement.
A man, 24, was taken into custody in Lambeth on suspicion of robbery and assault and a 23-year-old woman was detained on suspicion of conspiring to commit a robbery. Both individuals are still being held, authorities confirmed.
The arrests come after an investigation into an attack at the multi-storey car park at Heathrow's Terminal 3 on Sunday. Before the incident, a pair of female travelers were robbed of their luggage upon exiting a parking garage elevator.
A toddler aged three was among the those hurt in the event. Five people were taken to the hospital for medical care and were later discharged.
Police arrested a 31-year-old man for suspected theft and assault near the location. He was subsequently released under investigation while inquiries continue.
Police were alerted at about 8:10 in the morning GMT following reports of a number of people hurt by a noxious substance thought to be an irritant spray.
The attack - which authorities stated was isolated and not considered terrorism - resulted in delays to rail services and the temporary shutdown of the main airport tunnel and the Terminal 3 car park briefly.
