One man died outside a Muslim centre in the north of the city
One man has died in the UK after a van hit 11 worshippers leaving a Muslim welfare centre in London.
The Metropolitan Police said eight people have been taken to hospital after the collision in Seven Sisters Road, Finsbury Park.
A further two people were treated at the scene where police arrested a 48-year-old man who had been held by members of the public.
The UK's Counter Terrorism Command Unit is helping police with their investigation into the incident which witnesses described as a deliberate attack.
However it is not known if the man's death is directly related to the attack, as he was already receiving first aid from the public at the scene.
Police say any causative link between his death and the attack will form part of their investigation - but that it is "too early" to state if his death was as a result of the attack.
British Prime Minister Theresa May confirmed that the police were treating it as a potential terrorist attack and said she will chair an emergency response meeting on Monday.
Speaking to the media, Deputy Assistant Commissioner Neil Basu said: "No matter what the motivation proves to be, and we are keeping an open mind, this is being treated as a terrorist attack and the Counter Terrorism Command is investigating.
"This was an attack on London and all Londoners and we should all stand together against extremists whatever their cause."
He said police recieved a number of calls at 12:21am Monday morning.
"Officers were in the immediate vicinity as the attack unfolded and responded instantly. Additional officers arrived within 10 minutes."
"One man was pronounced dead at the scene. Eight others are in hospital and two more were treated at the scene.
"All the victims were from the Muslim community."
Metropolitan Police Commissioner, Cressida Dick, added: "London is a city of many faiths and many nationalities. An attack on one community is an attack on all of us.
"Terrorists will not succeed in their attempts to divide us and make us live in fear.
"Extra officers are on duty in the area to help reassure the local community. They will be there for as long as they are needed."
In a statement, London Mayor Sadiq Khan called it "a horrific terrorist attack":
The collision occurred outside Finsbury Park's Muslim Welfare House, which is nearby the Finsbury Park Mosque.
The Muslim Council of Britain (MCB) general secretary Harun Khan said: "During the night, ordinary British citizens were set upon while they were going about their lives, completing their night worship. It appears from eyewitness accounts that the perpetrator was motivated by Islamophobia.
"Over the past weeks and months, Muslims have endured many incidents of Islamophobia and this is the most violent manifestation to date.
"Given we are approaching the end of the month of Ramadan and the celebration of Eid with many Muslims going to local mosques, we expect the authorities to increase security outside mosques as a matter of urgency."
A delivery driver who was on a bike about three cars behind the incident, Mohammad Abdullah, said he saw the van take a sudden left turn.
"I think he done it on purpose. I was on a ped. He was about three cars in front of me. He came in a bus lane and took a sharp left.
"He went on top of the people. He actually ran them over. It was a white van.
"There was three of them. Two of them ran away. The other was held at the scene until the police came. Some people wanted to beat him up.
"I've seen about six or seven people on the floor. Most of them was male. It was exactly the same time as the prayers finished. As soon as it finished, this guy came. I think (the road he took) is a blocked road - It's not even a through road.
"The other two got away. They must be somewhere around Finsbury Park. They ran away somewhere."
"He had a tattoo on his back. He was not ill. He was not drunk. He got arrested by five or six police officers. They took him away. They never dropped him or nothing."
Toufik Kacimi, the chief executive of the Muslim Welfare House, said the man who was arrested had to be rescued by the imam at the centre to stop him being attacked, and when he did so, the driver said to him: "I've done my bit."
Pictures on social media suggest the collision occurred at the entrance to Whadcoat Street.
London Ambulance Service say sent a "number of resources" to the scene.
Dozens of police, fire and ambulance service vehicles have been sent to the area, armed officers are on the scene and a helicopter is overhead.
Police said in a statement earlier: "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. He will also be subject of a mental health assessment in due course.
"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."