teenager was rushed by a machete-wielding gang in front of screaming crowds after a meet-up in Hyde Park turned violent on Tuesday night.
Mobile phone footage from about 9pm shows the victim being chased by a group of masked men armed with foot-long zombie knives and poles.
As he desperately tries to flee he slips on the grass and was set upon by a man in a grey hoody before being kicked, stabbed in the chest and struck with poles in a brutal attack lasting less than 20 seconds.
A woman filming the attack screams and swears: “He got stabbed! There’s a knife, there’s a knife! Oh my God, oh s***, oh God.”
Using slang for a stabbing, a male voice in the crowd says: “He bored him! Oh s*** he bored him!”
Another clip shows the man being given a final blow to the chest as he lies motionless face-up in the grass area which had been packed minutes earlier.
Police said the victim was expected to survive the encounter as they appealed for the public’s help in trying to identify the attackers.
A Met spokesman said: “He has been taken to hospital where his injuries were assessed as non-life threatening.
“An investigation is underway.
“At this stage there have been no arrests.
“There were lots of people in the park at the time of the incident and officers are appealing for witnesses to come forward.”
The daylight attack came just over an hour after another man, aged 23, found police officers after being stabbed in the face in Hither Green Lane, south London.
He was taken to hospital where he is fighting for life.
And on Sunday, police dog Kaiser was stabbed up to five times on the top of his head and once below his eye in Orpington.