A man is in hospital after being stabbed in the head, chest and arms in the seaside town Bognor Regis.
The victim is believed to be in his 20s and was found bleeding “quite heavily” after the emergency services were called at around 5.30pm on Sunday, Sussex Police said.
He was taken to the Royal Sussex County Hospital in Brighton.
A suspect ran off from Marine Park Gardens, leaving the victim, but was detained about ten minutes later.
A 23-year-old man from Barnet, London, was arrested on suspicion of attempted murder and remains in custody.
It is the latest wave of knife crime witnessed in the UK, with one police commissioner warning of a “national emergency”.
Sussex Police said: “Anyone who witnessed the incident is asked to report online or call 101 quoting serial 1237 of 10/03. If you see anyone with a knife in the street, please dial 999 immediately.”