A man has been rushed to hospital by air ambulance after he was attacked in Edgware on Sunday afternoon.
An air ambulance was seen taking off from close to the location of the broad daylight attack that is now under investigation.
Armed Police officers from the Met Police attended to support local officers.
Police have established a crime scene within parts of Whitchurch Lane they have also cordoned off near to a parade of shops
A spokesman for the Met Police say they have launched an investigation following a stabbing attack and would urge anyone who saw the attack to contact them on 101.
A spokesman said more details would be released later.
More to follow