Police say one person was killed and 10 injured.
The person arrested in connection with the incident was a 48-year-old who was driving the van.
Britain’s Muslim council condemned what it called an attack on worshipers as they were leaving prayers at the mosque.
A witness described the scene as a van drove into people who were leaving a mosque in North London just after midnight on Sunday, local time.
Police said a vehicle struck an unknown number of pedestrians, causing several casualties.
One person has been arrested.
The London ambulance service said the injured were taken to hospitals.
Witnesses reported seeing police give emergency medical treatment to some of the injured.
The British Muslim Council tweeted that worshipers were struck by a van as they were leaving prayers at the Finsbury Park Mosque.
One wwitness told British Television there were three people in the van.
He said one of them was arrested, and the other two got away.
Police say they are investigating this as a terror attack.
This is a developing story, stick with us for the latest updates.