A 47-year-man has been arrested on suspicion of terrorism offences after allegedly ploughing a van into a group of worshippers leaving a mosque in Finsbury Park, North London.
The man was arrested on suspicion of attempted murder at the scene following the attack just after midnight on Seven Sisters Road outside the Muslim Welfare House which killed one and injured nine.
Scotland Yard released a statement saying the man has now been additionally arrested on suspicion of offences of murder and the commission, preparation or instigation of terrorism.
Deputy Assistant Commissioner Neil Basu says: "This is being treated as a terrorist incident and is being investigated by the Counter Terrorism Command.
"All the victims were from the Muslim community and we will be deploying extra police patrols to reassure the public, especially those observing Ramadan.
"We are working hard to protect all communities and the public will see additional officers patrolling across the city and at Muslim places of worship. This was an attack on London and all Londoners. We should all stand together against extremists whatever their cause."
They also confirmed they were carrying out searches at a residential address in the Cardiff area in connection with the attack.
The alleged victims are believed to have been leaving the mosque after attending prayers and eating their evening iftar meal to break their fast for Ramadan.
The man who died is believed to have collapsed and was being attended to by other worshippers when they were attacked.
He was pronounced dead at the scene at around 1am. Police say inquiries are continuing to establish whether his death was a direct result of the attack.
The attack happened just days after worshippers at the mosque where warned about the increased risk of hate crime against during their holy month.
Islamophobia charity Tell MAMA urged the mosque to remain vigilant during Ramadan as they were at increased risk of being targeted as they more likely to be wearing traditional dress which would identify them as Muslim.