A 14-year-old schoolboy was among three teenagers knifed during a quadruple 'gang' stabbing yesterday in Bromley.Those youngsters, including four more aged between 14 and 17, have since been arrested on suspicion of attempted murder.Witnesses say a bloody 'gang' battle started in a KFC restaurant before it spilled out onto the street in front of horrified shoppers.Air ambulance medics rushed to the scene on Bromley High Street in south-east London just after 2pm and found a man aged 21 with serious stab wounds.He was rushed to hospital in a critical condition, but his injuries have now been deemed non life-threatening, the Met Police said.The man has also been arrested on suspicion of attempted murder, as officers try to piece together what happened in the chaos.Sergey Kucherenko, 36, said he saw a 'pack of youths' chasing each other from KFC towards the direction of a nearby park.He told the Daily Mail: 'At first I thought it was just school kids creating problems, which is a common thing now. Police officers outside a KFC in Bromley, south-east London, yesterday following the stabbing Forensic investigators scour the scene outside the KFC in Bromley yesterday afternoon'But I could hear screaming, and some of the boys were trying to grab the others and they were fighting and there was blood.'It was obviously gang related. But I was confused, because they looked so young, but were waving huge knives about.'Forensics officers were seen combing the popular eatery for clues - after placing several yellow markers down on the restaurant floor.An emotional friend of one 14-year-old boy who was stabbed last night said he was cut down by gang members 'for no reason at all'.He told the Daily Mail: 'He was innocent, he doesn't do anything bad. The most bad thing he has done is get a detention.'He is a loyal person, he is like the best person that you could actually meet. He was out near the high street when he was attacked. They just done it. They were gang members.'The friend added: 'You see those kind of people [gang members] - if you take their weapons away they are just weak.'One shopkeeper, speaking on condition of anonymity, said gangs were becoming a big problem for local residents and business owners.He said: 'You get loads of kids running in here, filming everything, thinking everything is a joke, breaking things, stealing items. Emergency services descend on the KFC in Bromley yesterday following reports of a stabbing Police in Bromley yesterday after four people were taken to hospital following the stabbing 'It's become a bit of a war zone. I was dreading them [children] going back to school, because they all get together in groups.'I've had to get more CCTV to deal with it. They get violent if you say anything back. Something needs to be done.'A cordon has been removed on the high street, but police remain a visible presence in the area.A major London Violence Reduction Unit analysis ranked Bromley just 23rd of London's boroughs for knife crime and 21st for violence with injury in the year to September 2023.Croydon, by comparison, ranked third for knife crime, while neighbouring Lewisham was 14th.Official Bromley figures show the number of knife crimes recorded across all age groups rose from 533 in 2021 to 689 in 2022 and 764 in 2023, an increase of more than 43 per cent in just two years.M20, a nearby Penge-based gang identified by Bromley safeguarding officials, has been linked to knife crime, robbery, drugs, exploitation and serious violence across the area and south-east London.A Metropolitan Police spokesman said: 'At around 2:15pm on Thursday, September 10, officers were called to reports of an altercation on Bromley High Street.'Officers attended the scene alongside the London Ambulance Service and London's Air Ambulance and found three boys, aged between 14 and 17, and a 21-year-old man suffering from stab wounds. Police give directions to members of the public from behind a cordon in Bromley yesterday Forensic investigators work inside the KFC on Bromley High Street yesterday afternoon'The boys were taken to hospital where they received treatment for non-life-threatening injuries.'The man was also taken to hospital in a critical condition, however, following medical assessment, his injuries have since been deemed non-life-threatening.'All four of those injured, along with four other boys aged between 14 and 17, have since been arrested on suspicion of attempted murder and remain in police custody.'Chief Inspector David Cooper said: 'We recognise the impact this incident will have on the local community, and officers are working quickly to establish the full circumstances.'There will be an increased police presence in the area, and we encourage anyone with information or concerns to speak to officers.'The Met spokesman added: 'This incident is being treated as an isolated incident.'Officers are appealing to anyone who may have footage or information relating to the incident to contact police on 101, quoting CAD 4008/10SEP, or Crimestoppers anonymously on 0800 555 111.'A KFC spokesperson confirmed a 'serious incident' had taken place at its restaurant and an altercation had begun there.The fast food chain said it was assisting police and 'supporting our team members and customers at this difficult time'.