A man is fighting for his life after a stabbing in Hyde Park, police confirmed.
The victim, believed to be in his 20s, was reportedly knifed at around 4.40pm after a fight broke out.
Investigators say it happened in the western side of the park.
A Metropolitan Police spokesman said: "Police were called at around 4.40pm on Saturday, 20 April, to a fight in the western part of Hyde Park, W1.
"Officers attended along with London Ambulance Service and found a man suffering a suspected stab injury.
"The man, believed to be aged in his 20s, has been taken to hospital.
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"His condition is being treated as potentially life-threatening at this stage. We await a further assessment.
"Detectives from the Central West Command Unit are investigating."
No arrests have been made in connection with the stabbing.
The stabbing happened on a day when thousands gathered in the park to mark 420 day - an unofficial cannabis protest - and climate change activists from Extinction Rebellion are demonstrating at nearby Marble Arch.
Anyone with information is asked to call police via 101 quoting reference 5053/apr20. To remain anonymous call Crimestoppers on 0800 555 111.
