A bizarre incident unfolded at Heathrow airport Terminal 3 on Sunday, December 7 where a group of men reportedly sprayed several people with pepper spray.
The police said armed officers were called to the scene at around 8:11 am after the incident was reported.
A statement by the force said, "A number of people were sprayed with what is believed to be a form of pepper spray by a group of men who then left the scene," as per Sky News.
One man was arrested on suspicion of assault and he is still in custody while officers continue looking for other suspects.
As per the outlet, the London Ambulance Service treated 21 people at the scene with five taken to the hospital and their injuries are not considered as life-threatening.
Commander Peter Stevens said in a statement, noting, "At this stage, we believe the incident involved a group of people known to each other, with an argument escalating and resulting in a number of people being injured."
He added, "Our officers responded quickly and there will be an increased police presence at Heathrow Airport throughout the morning, to continue enquiries and ensure the safety of those in the area."
The police have further confirmed that the incident at Heathrow is not being treated as a terrorist attack.
