Police were called just before 4pm yesterday (November 4) to Essex Road near Rotherfield Street.
A man in his 40s with injuries to his neck was rushed to hospital “as a priority”.
The severity condition is currently being assessed.
A trail of blood could be seen in front of Essex Road Supermarket, café and post office.
Blood spatters were left on the seats and tables of cafes even after an earlier police cordon was cleared.
There have been no arrests and police are appealing to the public for any information.
A London Ambulance Service spokesperson said: “We were called at 3.59pm on Tuesday 4 November to reports of an incident on Essex Road, Islington.
“We sent ambulance crews and an incident response officer to the scene. We also dispatched a trauma team in a car from London’s Air Ambulance.
“Our first paramedics arrived on scene in three minutes.
“We treated a man at the scene and took him to a major trauma centre as a priority.”
A spokesperson for the Met Police said: “Police were called at 15:58hrs on Tuesday, 4 November following reports of an injured man on Essex Road, Islington.
“The victim, a man in his 40s was taken to hospital with injuries to his neck. He remains in hospital and his condition remains under assessment.
“Officers carried out searches in the area, and no arrests have been made at this stage.
“Enquiries remain ongoing.
“Anyone with information is asked to contact police on 101 or online, quoting CAD 5179/04NOV.”
