British media reports said that a crowd had gathered outside the mosque Sunday night to help an elderly worshiper who had collapsed; the man died after the attack, but it was unclear whether his death was due to the attack itself.
Metropolitan Police Commissioner Cressida Dick added: "We are here as you are well aware because of the awful, bad attack that took place last night".
The Finsbury Park mosque in north London said the van "deliberately mowed down Muslim men and women leaving late evening prayers" at the mosque and the nearby Muslim Welfare House shortly after midnight. Many police cars and ambulances were responding.
Speaking to reporters Monday, the imam, Mohammed Mahmoud, said he and others acted to "extinguish any flames of anger or mob rule that would have taken charge had this group of mature brothers not stepped in".
On Monday, police said that all of the victims outside the mosque were from the Muslim community, but it was "too early to tell" if the man who died at the scene did so as a result of the attack. "Eight people injured were taken to three separate hospitals; two people were treated at the scene for minor injuries".
Locals held onto the suspect until he was detained by police and later arrested on charges of "the commission, preparation or instigation of terrorism including murder and attempted murder". Police are treating the incident as a terrorist attack.
Suspect in London van attack identified as Darren Osborne
The imam of Muslim Welfare House - which is also a community centre - said a passing police van was flagged down after the attack. The incident comes at a time when emotions are high in England, where there have been several recent terrorist attacks.
London Mayor Sadiq Khan said "terrorism is terrorism".
The imam who protected the suspect in the Finsbury Park attack has spoken of how he and other worshippers did their best to "extinguish any flames of anger or mob rule".
"Today we come together as we have done before to condemn this act and state again that hatred and evil of this kind will never succeed", the Prime Minister continued.
The secretary general of the Muslim Council of Britain, Harun Khan, tweeted that the van had "intentionally run over worshippers" and that he was "shocked and outraged". One person was killed in the incident.