Police were called just after 0020hrs 19 June to reports of a van in collision with pedestrians.
Officers attended alongside other emergency services and found and tended to a number of casualties.
One man was pronounced dead at the scene. Officers are in the process of informing next of kin. A post mortem examination will be scheduled due course.
Eight people injured were taken to three separate hospitals; two people were treated at the scene for minor injuries.
At this stage there are no reports of any persons having suffered any knife injuries.
The driver of the van - a man aged 48 - was found detained by members of public at the scene and then arrested by police in connection with the incident.
He has been taken to hospital as a precaution, and will be taken into custody once discharged.
A number police units are at, and managing the cordons around, the crime scene, including local officers and those from neighbouring boroughs - supported by armed officers and the Territorial Support Group.
The investigation of the incident is being carried out by the Counter Terrorism Command.
At this early stage of this investigation, no other suspects at the scene have been identified or reported to police, however the investigation continues.
Due to the nature of this incident extra policing resources have been deployed in order to reassure communities, especially those observing Ramadan.
Any witnesses, or anyone with any information, can contact police via 101, or via Twitter @MetCC, or online here.
To give information anonymously call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
When more information has been confirmed as accurate, it will be released as appropriate in due course
A503 Seven Sisters Rd is now closed between Hornsey Rd and Blackstock Road. Isledon Road is also closed.
Updates will be posted on the Met's news desk here.
Follow https://twitter.com/metpoliceuk for updates.
For information on bus diversions go to https://tfl.gov.uk/bus/status/.