One person was arrested following the incident 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".
The Muslim Council of Britain (MCB) said a van "intentionally" ran over people.
Witnesses said the area was busy because worshippers had been attending evening prayers.
London Ambulance Service said it had sent "a number of resources" to the scene.
One eyewitness who lives in a flat on Seven Sisters Road told the BBC she saw people "shouting and screaming".