0216 GMT December 16, 2017
Prime Minister Theresa May condemned the "sickening" incident, saying Britain's determination to fight "terrorism, extremism and hatred... must be the same, whoever is responsible", AFP reported.
The 48-year-old driver of the van, a white man who police believe acted alone, was detained by people at the scene before being arrested on suspicion of attempted murder.
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.
Others linked the attack to an increase in anti-Muslim hate crimes, particularly since the London Bridge rampage on June 3 that left eight people dead, which was claimed by the Daesh terror group.
"This was an attack on London and all Londoners and we should all stand together against extremists whatever their cause," said Neil Basu, senior counter-terrorism officer for the Metropolitan Police.
He added that it had "all the hallmarks" of a terrorist attack.
It unfolded as a man was receiving first aid from members of the public in an unrelated incident. The man later died, though it is not yet clear whether his death was linked to the attack, Basu said.
Ten people were hurt, all of them Muslims, with eight of them requiring hospital treatment. Two of them were in a very serious condition, police said.
A witness, Abdiqadir Warra, said that the van "drove at people" and that some of the victims were carried for several meters along the road.
"He was shouting: 'All Muslims, I want to kill all Muslims'," another witness, Khalid Amin, told BBC television.
Basu praised locals for detaining the man, saying that their "restraint in the circumstances was commendable".
Community in shock
The use of a vehicle to mow down pedestrians drew horrifying parallels with the June 3 attack, when three men drove a van into pedestrians before embarking on a stabbing spree, and with another car and knife rampage in Westminster in March.
This time, however, the attacker appeared to have deliberately targeted at Muslims.
"Over the past weeks and months, Muslims have endured many incidents of Islamophobia and this is the most violent manifestation to date," said Harun Khan, head of the Muslim Council of Britain (MCB), an umbrella body.
After the London Bridge attack, the mayor's office reported a 40 percent increase in racist incidents in the city and a fivefold increase in the number of anti-Muslim incidents.
Mohammed Kozbar, chairman of the Finsbury Park Mosque, described it as "cowardly".
"Our community is in shock," he said, urging people attending prayers to remain vigilant.