Two more people are now in custody in connection with a robbery at Heathrow Airport in which 21 people sustained injuries 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 23-year-old woman was detained for suspected conspiracy to commit robbery. Both individuals are still being held, the force said.
The arrests follow an investigation into an attack at the multi-level parking garage at Terminal 3 on Sunday. Prior to the incident, two women 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 arrested a man in his thirties on suspicion of theft and assault near the scene. He was subsequently released under investigation as the investigation proceeds.
Police were alerted at about 08:10 GMT following reports of a number of individuals hurt by a noxious substance believed to be an irritant spray.
The attack - which authorities stated was a standalone incident and not being treated as an act of terror - resulted in delays to rail services and the temporary shutdown of the Central Terminal Area tunnel and the Terminal 3 parking facility briefly.
