Two more people are now in custody related to a robbery at London's Heathrow Airport in which 21 people sustained injuries by a substance believed to be an irritant spray, as stated by police.
A 24-year-old man, was arrested in Lambeth on suspicion of theft and assault and a woman, 23 was detained for suspected conspiring to commit a robbery. They both are still being held, the force said.
The arrests come after an investigation into an assault at the multi-level parking garage at Heathrow's Terminal 3 on Sunday. Before the attack, a pair of female travelers had stolen from them their luggage after getting out of a parking garage elevator.
A three-year-old girl was among the those hurt in the event. Five people went to hospital for treatment and have since been released.
Officers detained a 31-year-old man for suspected robbery and assault close to the scene. He was subsequently released under investigation while inquiries continue.
Police were alerted at about 08:10 GMT following reports of several people injured by an irritating chemical believed to be pepper spray.
The assault - an event that police said was a standalone incident and not considered terrorism - resulted in train delays and the partial closure of the Central Terminal Area tunnel and the Terminal 3 car park briefly.
