LONDON (AP) -- A white man plowed a van into a crowd of Muslim worshippers outside a north London mosque early Monday in an attack that police say they are investigating as a terrorist incident.
Ten people were injured in the attack and police said another man died at the scene, though he was receiving first aid at the time and it wasn't clear if he died as a result of the attack or of something else.
British Prime Minister Theresa May condemned the attack "on innocent people" and declared that Britain would stop at nothing to defeat extremism.
"Hatred and evil of this kind will never succeed," she said in a televised statement.
Police said the 48-year-old man who was driving the van that hit people leaving evening prayers at the Finsbury Park mosque has been arrested on suspicion of attempted murder. Police have not released his identity. He has been taken to a hospital as a precaution.
Metropolitan Police Deputy Assistant Commissioner Neil Basu said police are investigating whether the death of the man getting first aid was a direct result of the attack, but it was too early to say for sure.
London police - already stretched by a series of tragedies including a June 14 high-rise apartment fire in which 79 people are presumed dead and a June 3 terror attack near London Bridge that killed seven people - said they are putting more officers on the street to reassure the public. Muslim leaders called for calm.
London Mayor Sadiq Khan, the first Muslim to serve in that position, urged residents to focus on their shared values and to stand together during this an unprecedented period in the capital's history. The attack on Monday hits a community already feeling targeted in the fallout from the London Bridge killings and other attacks blamed on Islamic extremists.
"While this appears to be an attack on a particular community, like the terrible attacks in Manchester, Westminster and London Bridge, it is also an assault on all our shared values of tolerance, freedom and respect," Khan said. "The situation is still unfolding and I urge all Londoners to remain calm and vigilant."
British security officials, speaking on condition of anonymity in line with official policy, said hate crimes directed at Muslims have increased nearly five-fold in the wake of several attacks in Britain.
Counter-terror officials said they were closely monitoring terror activity linked to far-right groups but most of the recent attacks have been traced to individuals rather than groups.
Sky News reported that the mosque's imam prevented the crowd from beating the attacker until police arrived.
Toufik Kacimi, chief executive of the Muslim Welfare House, speaking to Sky News, said 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 the attack also laid bare the frustrations of a community who believe they've been unfairly equated with extremists who have carried out atrocities in the name of Islam. Early police caution about declaring the incident to be terrorist-related was interpreted by the community as discriminatory.
May attempted to counter that feeling in her speech, declaring that police arrived at the scene within one minute, and that a terror attack was declared in eight minutes.
Ali Habib, a 23-year-old student, said residents are angry that the mosque attack hasn't been portrayed in the same light as the other attacks across the country.
"There has been an outpouring of sympathy for all for the recent terror attacks but hardly a whisper on this attack," he said. "People are both scared and angry. Parents are scared to send their children to evening prayers. I don't think people understand how much these attacks affect all of us."
The Finsbury Park mosque was associated with extremist ideology for several years after the 9/11 attacks in the United States, but it 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.
May said she would chair an emergency security Cabinet session Monday. She said her thoughts were with the injured, their loved ones and emergency officials who responded to the incident.
Britain's terrorist alert has been set at "severe," meaning an attack is highly likely.
Earlier this month on London Bridge, Islamic extremists used a vehicle and then knives to kill eight people and wound many others on the bridge and in the popular nearby Borough Market area. The three Islamic extremists who carried out the attack were killed by police.
In March, a man plowed a rented SUV into pedestrians on Westminster Bridge, killing four people before stabbing a police officer outside Parliament.
Manchester was also hit on May 22 when a suicide bomber killed 22 people at an Ariana Grande concert.