London Metropolitan Police said Monday that they are working with counter-terrorism officials in their investigation of an attack on worshippers leaving a north London mosque late Sunday that may have killed at least one person and left dozens injured.

The attack, the fourth deemed terrorist-related by British security officials so far this year, occurred in the Finsbury Park area of London late last night, when police say a 48-year-old man mounted the sidewalk in the van he was driving and ploughed into members of a local mosque who were exiting from evening prayers just after midnight local time.

Counter-terrorism officials said the driver targeted people who were assisting a man who had collapsed outside the mosque, who later died at the scene, adding that "any causative link between his death and the attack will form part of our investigation. It is too early to state if his death was as a result of the attack."

"No matter what the motivation for this attack proves to be we are keeping an open mind. This is being treated as a terrorist attack and the counter-terrorism command is investigating," Deputy Assistant Commissioner Neil Basu said in a statement. "This was an attack on London and all Londonders and we should all stand together against extremists whatever their cause."

"Given the methodology and given what was occurring and what's happened across the country this had all the hallmarks of a terrorist incident," the statement added.

Cmsr: "There is now an ongoing investigation by our Counter Terrorism Command to establish why this attack was carried out."

— Metropolitan Police (@metpoliceuk) June 19, 2017

The driver of the van was arrested and detained by police, with some eye-witness reports suggesting he had been protected from harm by the F

U.K. Prime Minister Theresa May said Monday that she will chair a meeting of the Cabinet Office Briefing Room, known as COBRA, which puts domestic security officials and senior members of the government together during crisis issues such as terrorist attacks.

PM: Appalled by the terrible incident in Finsbury Park. My thoughts & prayers go out to the victims, their families & the emergency services

— UK Prime Minister (@Number10gov) June 19, 2017

PM: This morning, I will lead an emergency meeting of COBR.

— UK Prime Minister (@Number10gov) June 19, 2017

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