Armed police were sent to a shopping centre in Bromley, Kent, after receiving reports of a man carrying a large knife.
Videos from the scene show crowds of panicked Boxing Day shoppers fleeing the shopping centre after an incident, with bystanders reporting seeing large numbers of people running away from the area on Boxing Day afternoon.
Images from the Intu shopping centre (formerly known as the Glades) in the middle of the town appeared to show police officers carrying a large, machete-like weapon away from the scene.
One witness wrote on Twitter: "What the **** happened in Bromey? People running out of the Glades, people screaming."
According to a spokeswoman for the Metropolitan Police, officers were called at around 3:45pm to reports of an injured man at the shopping centre, which was filled with shoppers taking advantage of the Boxing Day sales.
Attending, officers found a man in his 20s with a head injury, which they believed he sustained in an altercation.
The injured man was arrested on suspicion of affray and possession of an offensive weapon.
Officers recovered two knives and were looking to trace a man of whom they had no further details, who they believe ran from the scene, possibly discarding a weapon as he fled.
Police confirmed that the incident was not related to terrorism.
The Intu shopping centre confirmed via Twitter that police were called on Boxing Day, and added the centre was remaining open and trading until closing time at 6PM.
London Ambulance Service said one woman was treated at the scene, but she was not sent to hospital.
The Metropolitan Police urged anyone who witnessed the incident, or anyone with photos or videos from the scene, to contact them on the 101 non-emergency number.
