According to reports, at least ten people were hit outside the mosque with three of them being critically injured.
Kacimi said when he did so, the 48-year-old driver said to him: "I've done my bit".
She said the road was "backed up" with police cars, ambulance and fire engines.
Neither the identity of the man nor his motives have been revealed so far. Eight people injured were taken to three separate hospitals, with two being treated at the scene for minor injuries.
Abdulraman Aidroos, who witnessed the incident, said "a white British man" shouted, "I am going to kill Muslims" before driving his vehicle into pedestrians.
Harun Khan, the head of the MCB, described the incident as the "most violent manifestation to date" of Islamophobia, and called on authorities to do more "to tackle the growth in hate crime".
Labour Party leader Jeremy Corbyn released a statement on Twitter following the incident.
According to the Council in a follow-up tweet, the van struck the victims closer to the Muslim Welfare House.
London police say one suspect has been detained in an apparent early-morning attack on worshippers standing outside a mosque.
Finsbury Park Mosque Chairman Mohammad Kozbar lamenting over the incident, "Our thoughts and prayers with those who got injured and effected by this cowardly attack".
The incident follows a series of attacks in Britain.
"The Met have deployed extra police to reassure communities, especially those observing Ramadan".
"This big van just came and went all over us", witness Abdulrahman Saleh Alamoudi told BuzzFeed News.
The Finsbury Park mosque has been associated with hate preacher Abu Hamza and a number of terrorists including shoebomber Richard Reid who attempted to detonate explosives on a flight from Paris to Miami in 2001. The incident comes after terror attacks in Manchester and London in recent, the latter of which involved, in part, a van striking pedestrians on London Bridge.
The Home Secretary confirmed that counter-terrorism police officers were involved in the investigation.
The Muslim Council says a van has "run over worshippers" leaving the mosque and the council tweeted that its prayers were with the victims.