A vehicle struck pedestrians near a mosque in north London early Monday morning, causing several casualties, police said.
One person has been arrested. London Ambulance Service says the injured are being taken to hospitals.
Eyewitnesses reported seeing police give emergency medical treatment to at least one of the injured.
The Muslim Council tweeted that worshippers were struck by a van as they were leaving prayers near the Finsbury Park mosque. It said its prayers are with the victims.
The neighborhood has two mosques, and several hundred worshippers would have been in the area after attending prayers as part of the Muslim holy month of Ramadan.
The Finsbury Park mosque was associated with extremist ideology for several years after the 9/11 attacks in the United States but was shut down and reorganized. It has not been associated with radical views for more than a decade.
London police have declared the crash a major incident and closed the area to normal traffic. A helicopter circled above the area as a large cordon was established to keep motorists and pedestrians away.
Metropolitan Police said officers were called to the scene on Seven Sisters Road at 12:20 a.m. Monday. Many police cars and ambulances responded to the incident.
No other details were immediately available.
Britain's terrorist alert has been set at "severe" meaning an attack is highly likely.
Earlier this month, a van veered into pedestrians on London Bridge, setting off vehicle and knife attacks that killed eight people and wounded many others on the bridge and in the nearby Borough Market area. Three Muslim extremists who carried out the attack were killed by police.
Manchester was also hit by a severe attack when a bomber killed more than 20 people at an Ariana Grande concert.