Police are appealing for information after a teenager was stabbed by an armed group in Hyde Park in front of horrified onlookers.
The unidentified 17-year-old was rushed to hospital following the attack, which took place at around 9pm on Tuesday as crowds gathered in the central London park to enjoy the sunshine.
Police said the victim suffered non-life-threatening injuries.
Shocking video footage that appears to show the moment of the stabbing quickly spread across social media.
The clip appears to show a group of men armed with large knives chasing after someone in front of crowds of people.
Onlookers can be heard screaming and seen fleeing as someone is chased before appearing to fall to the ground.
One clip posted online appears to show witnesses describing the weapons as “swords” and “machetes”.
A Metropolitan Police spokesperson said: “Police were called at 21:00hrs on Tuesday, 1 June to reports of an assault in Hyde Park.
“Officers attended with London Ambulance Service paramedics. They found a 17-year-old male who had been stabbed.
“He has been taken to hospital where his injuries were assessed as non-life-threatening.
“An investigation is under way. At this stage there have been no arrests.”
Anyone with information is urged to call 101 and providing the reference CAD7861/01JUN, or Crimestoppers, anonymously, on 0800 555 111.
Mayor of London Sadiq Khan described the incident as "absolutely appalling".
He added: "The police have my full support in apprehending those behind this cowardly attack which has left one teenager in hospital.
“Knife crime ruins lives and devastates communities."
Tuesday’s attack was the latest in a series of stabbings in London across the Bank Holiday weekend.
Hours before the incident in Hyde Park, a 23-year-old man was rushed to hospital with life-threatening injuries after being stabbed in the face in Lewisham, south London.
Meanwhile, a 20-year-old man was arrested on suspicion of murder after a flower seller was stabbed to death close to his stall in north London on Saturday afternoon.
Tony Eastlake, 55, known as the “flower man of Islington” by customers and his local community, died from a knife wound after being attacked on Essex Road just before 5.30pm.
On Sunday, police dog Kaiser was stabbed up to five times on the top of his head and once below his eye while out on patrol with his handler PC Mark Woolcott.
Woolcott and Kaiser were investigating reports of an intruder in the back of a house in Orpington at the time of the incident.
The man responsible for the attack has been detained under the Mental Health Act.
And on Bank Holiday Monday, 10 males aged from their teens to their early 20s were arrested after a teenager was stabbed to death in Montrose Park, Edgware.
An 18-year-old male was found suffering from a stab injury in a tennis court area of the park.
He was treated by London’s Air Ambulance and the London Ambulance Service at the scene but despite the best efforts of paramedics, he was pronounced dead at 7.19pm.
On Tuesday, the Metropolitan Police said 10 males have been arrested in connection with the incident on suspicion of offences including affray and murder, and remain in police custody.