A vehicle has struck pedestrians “leaving a number of casualties” in north London, police said.
One person was arrested following the incident near Finsbury Park Mosque on Seven Sisters Road.
Officers were called at 00.20 BST and remain at the scene, the Metropolitan Police said, describing it as a “major incident”.
London Ambulance Service said it had sent “a number of resources”.
Witnesses said the area was busy because worshippers had been attending evening prayers.
The Muslim Council of Britain said its “prayers are with the victims.”
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.”
Others have described seeing police tend to the injured.
One eyewitness 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.
-BBC
-Agencies
