The police arrested one man after several people were sprayed with what is believed to be "a type of pepper spray" at Heathrow Airport by a group of men before they fled the scene.
The disruption reportedly caused the airport traffic to be blocked and trains to be suspended, and the airport has advised its customers to "allow extra time when travelling to the airport and to check with their airline for any queries" on its website.
Armed officers were called to the scene and arrested one man on suspicion of assault. He remains in custody as detectives work to identify and locate additional suspects, said the police, Xinhua reported.
London Ambulance Service had treated the victims, who were taken to hospital, and police said their injuries are not thought to be life-changing or life-threatening.
Commander Pete Stevens from the Metropolitan Police said early indications suggest the altercation broke out among people who were known to one another, and added that police do not believe the assault is terror-related.
The incident has caused some traffic disruption around Terminal 3, though the terminal remains open.