A man died and at least eight people were injured after a van was rammed into a crowd of worshipers near a mosque in north London, in what police are treating as a terrorist attack.
Eyewitnesses reported chaotic scenes as the incident unfolded just after midnight, when worshippers had just finished evening Ramadan prayers.
A 48-year-old man was wrestled to the ground by members of the public and then arrested at the scene on suspicion of attempted murder, London's Metropolitan police said.
"This is being treated as a terrorist attack and the Counter-Terrorism Command is investigating," said Neil Basu, senior national coordinator for terrorism at the Met.
-- Police say they believe there was only one man in the van.
-- Investigation is being carried out by the Counter-Terrorism Command.
-- Prime Minister Theresa May will chair an emergency meeting Monday morning.
-- Muslim Council of Britain releases a statement calling it a "terror attack."
The van rammed into the worshipers on Seven Sisters Road, a busy thoroughfare in Finsbury Park, north London, near a Muslim community center and a mosque. All victims were Muslim, Basu said.
He confirmed witness accounts that the man found dead at the scene was already receiving first aid when the attack happened, adding it was unclear whether he died as a result of the attack. Eight other people were taken to hospital, two of whom were seriously injured, he said.
Muslim Welfare House CEO Toufik Kacimi said the attacker shouted "I did my bit, you deserve it." An immam prevented people from taking revenge on the man, he said.
"And thanks for our imam, Muhammed Mahmoud, who went quickly and grabbed the (attacker), because the people there were trying to hit and kick the guy, but he saved him and kept him safe until the police arrived."
Police believed that the alleged attacker acted alone, despite earlier reports from witnesses, who had said they saw two other people flee the scene.
Prime Minister Theresa May will chair an emergency meeting on Monday morning.
"All my thoughts are with the victims, their families and the emergency services on the scene," she said.
London Mayor Sadiq Khan called the incident a "horrific terror attack." "We don't yet know the full details, but this was clearly a deliberate attack on innocent Londoners, many of whom were finishing prayers during the holy month of Ramadan," Khan said.
The assault comes on the heels of another attack at London Bridge, in which three men rammed a van into pedestrians and went on a stabbing spree at nearby bars and restaurants, killing eight people. Monday's attack is the third in London since March involving a vehicle as a weapon against pedestrians.
Emotions are high in the UK in the wake of a series of deadly terrorist attacks and a fire at a London apartment building that killed dozens. Basu said that the city's emergency services are stretched.
Witnesses told CNN they saw a van driving at high speed along Seven Sisters Road.
Abdikadir Warfa, who was on the street at the time, said the van turned into an alleyway and hit a number of people before coming to a stop. Images from the scene show a white van wedged against a traffic barrier at the dead end of a street.
"I saw a man, he was underneath the van," Warfa said, who described how his friends tried to lift the van to free him.
Warfa said many of the people in the street were worshipers who'd been attending late-night taraweeh prayers at the Finsbury Park Mosque.
He said as he attended the injured, others grappled with the driver as he tried to run away.
"The man tried to escape. My friends told me there were two other guys with him but they caught the driver," said Warfa.
Ratib Al-Sulaman told CNN he was sitting with friends two minutes away, when an "incident in front of the mosque" occurred.
"Some big van ... crushing the people in the mosque. So we just run straight away, I see police, ambulance, people lying on the floor, and a van as well," said Al-Sulaman. "There was three people in the van. One has been arrested and two ran away," he added.
Saeed Hashi described how he fought with the driver as he waited for police to arrive.
"We stopped the guy and we put him on the floor and people managed to call police," Hashi said, showing CNN his bruises. "He punched me in the head."
Hashi was one of three people who held the suspect on the ground for 10 minutes. "He was really shouting and aggressive ... he was just spitting on us," Hashi said.
Witnesses described seeing between eight to 10 people lying on the ground near to the Muslim Welfare House on Seven Sisters Road.
"I saw something that was horrendous, something we should not see the in the 21st Century, something we should not see in the last 10 days of Ramadan," said Mohammed Abdul.
Warnings of anti-Islamic attacks
A statement released by the Muslim Council of Britain (MCB) condemned what it described as a "terror attack."
"During the night, ordinary British citizens were set upon while they were going about their lives, completing their night worship. My prayers are with the victims and their families," read the statement.
Tell MAMA, an anti-Islamophobia group, had visited Muslim Welfare House on Friday last week to inform the community about the need to report anti-Muslim hate incidents and to consider their safety during Ramadan.
"Ramadan is a time when Muslims are more visible and when there are larger congregations who attend late at night to pray after opening their fasts. Mosque safety needs to be stepped up and this includes entry and exit points," it said in a statement.
Finsbury Park, in the London Borough of Islington, is a bustling, diverse area of north London with a strong Muslim community.
On May 22, a suicide attack killed 22 people and injured nearly 60 after an Ariana Grande concert in Manchester. The attacker was motivated by Islamist extremism, police said.
The London Bridge attack was on June 3. That attack also appeared inspired by Islamist extremism.
The head of Tell MAMA, Fiyaz Mughal, warned of reprisal attacks against Muslims following major Islamist terrorist incidents.
"We saw that very clearly after Manchester, a very high peak. We saw that clearly after London Bridge," he said.