A man has died and eight people have been injured after a van ploughed into pedestrians near a north London mosque.
The van mounted the pavement and struck a group of people just after midnight near Finsbury Park Mosque in Seven Sisters Road. A 48-year-old man has been arrested.
Counter terrorism officers are at the scene, the Metropolitan Police said.
The Muslim Council of Britain (MCB) said a van “intentionally” ran over worshippers.
Many of the victims are believed to have just left evening prayers at the Muslim Welfare House after breaking the Ramadan fast.
The MCB said it was a “violent manifestation of Islamophobia” and called for extra security around mosques.
Prime Minister Theresa May will chair an emergency meeting later and said police were treating it “as a potential terrorist attack”.
She described it as a “terrible incident”, adding: “All my thoughts are with those who have been injured, their loved ones and the emergency services on the scene.”
The van driver was arrested after being detained by members of the public at the scene following the collision at 00:20 BST.
Abdulrahman Saleh Alamoudi said he was among a group of people helping an elderly worshipper who had fallen down when the van swerved towards them.
Video posted online of the aftermath showed a scene of chaos as people tried to help the injured.
One man could be seen giving CPR to a victim in the street while another man’s head injury was treated with a makeshift dressing.
An eyewitness told how he jumped out the way of the van as it struck.
He said: “He just came into all of us. There was a lot of people. We got told to move straight away.
“I was shocked, shocked, shocked. There were bodies around me.
“Thank God I just moved to the side. I just jumped. Everyone is hurt. Everyone is actually hurt.”
Another who lives in a flat on Seven Sisters Road told the BBC she saw people “shouting and screaming”.
“Everyone was shouting ‘a van’s hit people’.
“There was this white van stopped outside Finsbury Park Mosque that seems to have hit people who were coming out of the mosque after prayers finished.”
She said the road was “backed up” with police cars, ambulance and fire engines.
Some witnesses at the scene – near Finsbury Park Station and the Emirates stadium – said more than one attacker may have been involved.
But the Met said: “At this early stage of this investigation, no other suspects at the scene have been identified or reported to police, however the investigation continues.”
Labour leader and Islington North MP Jeremy Corbyn said on Twitter: “I’m totally shocked at the incident at Finsbury Park tonight.
“I’ve been in touch with the mosques, police and Islington council regarding the incident. My thoughts are with those and the community affected by this awful event.”
‘Horrible to watch’
London Ambulance Service deputy director of operations Kevin Bate said: “We have sent a number of ambulance crews, advance paramedics and specialist responses teams to the scene.
“An advance trauma team from London’s Air Ambulance has also been dispatched by car.
“We are working closely with other members of the emergency services at the scene.
“Our priority is to assess the level and nature of injuries and ensure those in the most need are treated first and taken to hospital.”
Witness Cynthia Vanzella said on Twitter: “Horrible to watch police officers doing cardiac massage at people on the floor, desperately trying to save them. I just hope they did.”
The MCB said its “prayers are with the victims.”