A man who reportedly announced he wanted to "kill Muslims" drove a van into a crowd early Monday morning in London's north end, striking several pedestrians near a mosque in the city. 

Police said the 47-year-old driver — Darren Osborne, a father of four who was living in Cardiff, Wales, according to British media  — has been arrested on suspicion of attempted murder and the "commission, preparation or instigation" of terrorism.

Osborne's mother, Christine, and sister, Nicola, have spoken to British media, and the family issued a statement saying, "We're devastated for the families, our hearts go out to those who've been injured."

A residential area in Cardiff is being searched, according to London's Metropolitan Police. 

British Security Minister Ben Wallace said authorities were aware of rising far-right activity but were not aware of the suspect before the attack near the mosque.

The crash occurred shortly after midnight, when the multi-ethnic neighbourhood was crowded with Muslims leaving a Finsbury Park mosque after Ramadan prayers. Muslim leaders called it a hate crime and asked the public to stay calm.

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Officials said at least nine people were injured and one person died at the scene. The London Ambulance Service said it transported nine people to hospital.

Two other people were treated at the scene for minor injuries. 

Police said it wasn't immediately clear what caused the fatality, noting that the person had apparently fallen ill prior to the attack. 

"A man was receiving first aid from the public at the scene" at the time of the attack, said deputy assistant commissioner Neil Basu, senior national co-ordinator for counterterrorism.

"It is too early to state if his death was as a result of the attack."

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Harun Khan of the Muslim Council of Britain — citing eyewitness accounts and videos taken at the scene — appeared to confirm this later in the morning. He said a "white man in a van intentionally plowed into a group of worshippers who were already tending to someone who had been taken ill." 

Eyewitnesses reported seeing police give emergency heart massage to at least one of the injured.

Witnesses told British media outlets, including the BBC and the Guardian, that the driver got out of the van and shouted he wanted to "kill Muslims." 

'People were screaming and shouting'0:27

In the chaos that followed, he was pinned by people in the crowd and detained until police arrived — protected from the angry mob by the mosque's imam and worshippers. 

Imam Mohammed Mahmoud told reporters he and "other brothers" were able to prevent further violence. 

"By God's grace, we were able to protect him from harm," Mahmoud said. 

Community leaders praised Mahmoud's efforts. 

"[The imam] saved his life basically," Toufik Kacimi, chief executive of the Muslim Welfare House, told Sky News.

Video from the immediate aftermath of the attack shows a man being put into the back of a police van while surrounded by an angry crowd. 

Someone in the crowd asks, "Why do you do that? Why?" 

Another voice yells, "No one touch him! No one! No one!"

Police officers are seen shouting at the crowd to move back. 

On Facebook, London Mayor Sadiq Khan, the first Muslim to serve in that position, called the incident a "horrific terrorist attack." 

'A truly horrific terrorist attack on our city'0:53

London police, already stretched by a series of recent tragedies including a highrise fire in which 79 people are presumed dead and an attack near London Bridge that killed seven people, said they are putting more officers on the street to reassure the public. 

Police closed the area to normal traffic. A helicopter circled above the area as a large cordon was established to keep motorists and pedestrians away.

Othman el Lotfi had just left the mosque with his family when the attack happened.

"My daughter was crying. My wife was shaking. I can't believe it, you know?" he told CBC's Nahlah Ayed. He added it was incumbent on the government to do something.

"I want is everybody to live [in] peace."

Britain Mosque Attack

People take part in a vigil at Finsbury Park in north London, where a vehicle struck pedestrians on Monday. (Frank Augstein/Associated Press)

Area resident Idil Ahmed, who lives in a tower block nearby, said she was awoken by phone calls from people worried about her. She had a view of what was going on below.

"Nobody slept last night really," she said. 

"Even when we went to the school when I dropped off my children … it was pure fear and anxiety, even the children.

"What has London come to? What has Britain come to? Can we get back to the way we used to be? Hopefully I hope we can."

It appears the driver acted alone, according to U.K. Prime Minister Theresa May, who condemned the "sickening" attack while lauding the bravery of those who detained the driver. 

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London police, already stretched by a series of recent tragedies, said they are putting more officers on the street in the wake of the attack. (Jared Thomas/CBC)

"Hatred and evil of this kind will never succeed," May said outside 10 Downing Street, her official residence, following a meeting with the emergency COBRA committee. 

"This morning we have seen a sickening attempt to destroy those freedoms and to break those bonds of citizenship that define our United Kingdom. It is a reminder that terrorism, extremism and hatred take many forms."

May said police were on the scene within one minute of the crash, and had declared it a terrorist attack within eight minutes — addressing criticism from some that authorities were slow to respond and, together with the media, may have taken too long to describe the crash as a terror attack. 

May's main political rival, Labour Party Leader Jeremy Corbyn, the MP for that part of London, called on the community to "stand united against those who seek to divide us" while visiting the scene. 

The chairman of the Finsbury Park mosque urged Muslims going to mosques to be vigilant.

Mohammed Kozbar said the Muslim community is "in shock." 

The Finsbury Park mosque was associated with extremist ideology for several years after the Sept. 11 attacks in the United States, but was shut down and reorganized. It has not been associated with radical views for more than a decade.

It is located a short walk away from Emirates Stadium, home of the Arsenal football club in north London.

Britain's terrorist alert has been set at "severe," meaning an attack is highly likely.

Earlier this month, a van veered into pedestrians on London Bridge, setting off vehicle and knife attacks that killed eight people and wounded many others on the bridge and in the nearby Borough Market area. Three Muslim extremists who carried out the attack were killed by police.

Manchester was also hit by a severe attack when a bomber killed more than 20 people at an Ariana Grande concert.

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A police forensics officer stands next to a van believed to be involved in the attack. (Carl Court/Getty Images)

With files from CBC News