LONDON — British authorities and Islamic leaders moved swiftly to ease concerns in the Muslim community after a man plowed a large van into a crowd of worshippers outside a north London mosque early Monday, injuring at least nine people.

British media named the suspect as Darren Osborne, 47-year-old father of four who was living in Cardiff, Wales. British Security Minister Ben Wallace said authorities were aware of rising far-right activity but the suspect was not known to them prior to the attack.

Police are treating the incident as a terror attack. One man died at the scene, although he had been receiving first aid at the time and it wasn’t clear if he died as a result of the attack or from something else.

The chaos outside the Muslim Welfare House in Finsbury Park follows three Islamist-inspired attacks over the past three months and a surge in hate crimes around Britain.

The Metropolitan Police Service, already stretched by its investigations of the earlier attacks and a high-rise apartment fire that is believed to have killed 79 people, immediately announced it was putting extra patrols on the streets to protect the public.

Police will assess the security of mosques and provide any resources needed ahead of celebrations marking the end of the holy month of Ramadan, Prime Minister Theresa May said.

“This was an attack on Muslims near their place of worship,” she said in a televised address. “And like all terrorism, in whatever form, it shares the same fundamental goal. It seeks to drive us apart – and to break the precious bonds of solidarity and citizenship that we share in this country. We will not let this happen.”

The attack occurred about 12:20 a.m. when a speeding van swerved into worshippers who were giving first aid to a man outside the mosque. That man later died.

Police said the attacker who drove the van has been arrested on suspicion of the commission, preparation or instigation of terrorism, including murder and attempted murder. A mob surrounded him and witnesses said the crowd began attacking him. A local imam, Mohammed Mahmoud, said he organized a group of people and shielded the man until police could take him away.

“By God’s grace, we were able to protect him from harm,” he said.

Toufik Kacimi, chief executive of the Muslim Welfare House, told Sky News the attack clearly targeted Muslims leaving evening prayers during Ramadan.

“We have a witness saying that the guy who did what he did, the driver of the van, said ‘I did my bit,’ which means he’s not mentally ill,” Kacimi said. “This person was conscious. He did what he did deliberately to hit and kill as many Muslims as possible, so he is a terrorist.”

But Kacimi said there was no need for the community to panic, because police and government officials have been “very, very supportive.”

“At this stage, we are calling for calm,” he said.

Mayor Sadiq Khan, London’s first Muslim mayor, urged residents to focus on their shared values and to stand together during an unprecedented period in the capital’s history. The attack Monday hits a community already feeling targeted in the fallout from the London Bridge killings and other attacks blamed on Islamic extremists.

British security officials said hate crimes directed at Muslims have increased nearly five-fold in the wake of several attacks.