A man in his 20s has died after being stabbed in a fight near Ealing Common, west London.
Officers from the Metropolitan Police were called to reports of a fight close shortly after 18:00 BST and discovered the man suffering from stab injuries.
Members of the London Ambulance Service and the air ambulance also attended, however the man was pronounced dead at the scene at 18:48.
His next of kin have been informed and a post-mortem will be held.
A man was arrested on suspicion of affray and was taken to a west London police station where he remains in custody.
Inquiries are ongoing.
Anyone with information is asked to call officers on 101.
A section 60 order is now in place for the Hillingdon and Ealing areas until 07:00 on Wednesday, allowing the police greater search powers for a limited period.
This order comes after a murder investigation was launched when a man was stabbed to death on a train at Hillingdon station shortly before 16:00 on Tuesday.