A man has died and eight people have been injured after a van struck a crowd of pedestrians near a north London mosque.
A 48-year-old man was arrested following the collision just after midnight near Finsbury Park Mosque in Seven Sisters Road.
Counter terrorism officers are at the scene, the Metropolitan Police said.
The Muslim Council of Britain (MCB) said a van “intentionally” ran over worshippers.
The body said it was a “violent manifestation of Islamophbia” and called for extra security around mosques.
Prime Minister Theresa May 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.”
Many of the victims are believed to have just left evening prayers after breaking the Ramadan fast.
London Ambulance Service said it had sent “a number of resources” to the scene.
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.
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.
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.”