A second teenager has been arrested over a Boxing Day row between youths believed to have involved a 2ft-long machete.
The boy, aged 16, was found at his home in Lewisham, London, and arrested this morning on suspicion of affray.
He was initially treated in a south London hospital after suffering a minor wound before being taken to a local police station.
The fight, which began in the Intu shopping centre, formerly The Glades, in Bromley, south-east London, sparked rumours that a gunman was on the loose and armed police were called.
Boxing Day shoppers told how they ran "for their lives" after a group of youths began to argue in a shoe shop.
A video posted on Twitter shows shoppers, including families, screaming and running out of the centre.
Those caught up in the panic shortly before 4pm on Saturday afternoon told how they feared there had been a terror attack.
Keith Moon, 35, an app developer, was out shopping with his wife when he suddenly saw people running through the centre.
He later saw a male youth in handcuffs and bleeding from the head being led away by police, who were carrying a 2ft-long machete.
Police said the first boy to be charged over the incident, also 16, remains in custody on suspicion of affray and possession of an offensive weapon. Two knives were recovered at the scene.
Metropolitan Police said: "Detectives are seeking to trace a number of youths who ran off from the scene shortly after the incident."
Mr Moon described the scene as "chaotic".
Eyewitnesses on Twitter described scenes of "panic" and said shoppers were "running for their lives".
Nelson Adeosun, 27, who works in television, said: "It was really busy because of the Boxing Day sales and there was a mass exodus of people on the ground floor. They were shouting and running.
Mr Adeosun, who was out shopping with his brother, said he feared for his life as he ran out of the building.
He said: "People were running, some with children, and they were dropping stuff. It was a stampede."