When Henry opened his phone to a new Snapchat message from a friend, nothing could have prepared him for what he saw.Sat within the confines of his iPhone screen was a video of his 15-year-old best friend dying, having been stabbed multiple times at a 'linkup' in Hackney, east London.Henry, 15, watched as his teenage best friend took his last breaths, surrounded by people thoughtlessly filming him gasping for air - footage that would later spread across social media.Brayan David Saldarriaga, from Haringey, north London, was allegedly murdered on Poplar Close on the evening of Monday May 25 among a gathering of teenage revellers. He was pronounced dead at the scene.Footage showed screaming teenagers sprinting away from the scene and towards the Hackney Marshes, as shots were fired in the background. One girl was heard shouting: 'He got done, oh my days, yo, he got done'.Brayan's death lays bare the deadly reality teenagers face in London, where rising violence is increasingly taking root at teenage 'linkups' that have sprung up across UK's residential areas, high streets and parks this year.Youngsters flocked to Clapham on May 24 where a 17-year-old boy was stabbed and panic unfolded in Brighton after another alleged stabbing.Fights also broke out on Seaham beach in Durham and in Southend, Essex, where police were filmed arresting a teenager. Teenager Brayan David Saldarriaga (pictured) was allegedly murdered on Poplar Close on the evening of Monday May 25 among a gathering of teenage revellers Screaming revellers sprinted away from the scene on the residential lane and towards Hackney Marshes Posters, created by AI, promoting these 'linkups' are being circulated on social media sites TikTok and Snapchat, encouraging teenagers to gather in what appears to be an organised fashionSo called 'linkups' encourage a large group to meet en masse at a particular time and place, often encouraging anti-social behaviour. A feared mob mentality can quickly take hold at these gatherings, inciting fights and drawing gangs who arrive looking for potential targets.Police said a fight spilled out of a house party last week, which led to Brayan's death. A 16-year-old, who cannot be named because of his age, has since been charged on Saturday with his murder.This environment has left teenagers fearful to join their friends in Sir Sadiq Khan's London, as figures show crime in the capital has soared since the Mayor of London came to power - despite his claims it is a 'safe city'. Teenagers have subsequently had to become attuned to potential threats, which now includes 'linkup' gatherings. 'I wasn't stupid enough to go to Poplar Close that day,' Henry, whose name has been changed, tells the Daily Mail.'It is not safe in London as a teenager. Everyone should feel safe, but the current dangers young people face is never going to stop.'Posters, created by AI, promoting these 'linkups' are being circulated on social media sites TikTok and SnapChat, encouraging teenagers to gather in what appears to be an 'organised' event.Footage posted on social media shows a group of teenagers brawling along Brighton seafront On Seaham beach, families with children watched on as a large crowd formed around an apparent fight that broke out in the scorching heatThe poster sells this pretence in sharing a location and date, along with a call to bring one's own speakers and drinks - and the promotion of the sale of drugs.However Henry tells the Mail that many of the events are anything but safe - set up loosely by teenagers themselves, they quickly become an alcohol-fuelled arena where fights break out and violence festers.'Sometimes nothing bad happens, it just depends on the day. But most of the time, it is just girls fighting. They fight over little arguments,' Henry says.The danger rises sharply on the postcode. He claims this is particularly true of Hackney, rather than other 'linkup' locations of west and south London, where gang rivalry is allegedly rife as members are able to target specific people.'Gangs don't personally make the posters but they will if they think certain people are going to go. They go to have an altercation, ' Henry says.'I'm scared it's going to happen to me. Hackney is not a safe area because of gang violence. Every gang has beef so it will just keep going on. Civilians get caught in the crossfire.'Gangs are not specifically trying to hit civilians, they are trying to hit gang members. So if you look like one, you can get hit. This is normally the stereotypes, mostly black people who are wearing black clothing.'Henry, who is preparing to take his GCSEs next year, said 'linkups' normally attract teenagers aged 14 to 19 years old, who fundamentally 'just want to have fun and meet with friends'. However this can quickly turn.