The suspect who reportedly plowed his van into a crowd of people on late Sunday evening at Finsbury Park Mosque in North London, apparently screamed and shouted that he meant to take the lives of "all Muslims". I tried to stop him (the suspect), some people were hitting him but I said stop him and keep him until the police came.
"He has further been arrested for the commission, preparation or instigation of terrorism, including murder and attempted murder", Scotland Yard police headquarters said in a statement.
"He has assured me that his team is fully engaged and working in partnership with the London Metropolitan Police as the investigation into the abhorrent attack at Finsbury Park gets under way", Mr Cairns said.
Imam Mohammed Mahmoud was hailed for his efforts to calm the chaotic situation in the aftermath of the attack and was said to have used his body to shield the suspected terrorist from the fury of onlookers.
I think it's significant that they had the reputation historically of being one of the most militant mosques in London.
"We came with a whole team just to show our support for the Muslim community", said volunteer Eli Feld, 29, whose force helps protect the area's Muslims too. Those who try to divide us and who aim to spread fear, hatred and division will not succeed.
London Mayor Sadiq Khan condemned the attack and said it was deliberate and targeted "innocent Londoners, many of whom were finishing prayers during the holy month of Ramzan".
A 48-year-old suspect, who has been described by witnesses as caucasian, has been taken into custody and police are treating the attack as terrorism. "This person was conscious".
"When he was running he was saying "I wanna kill more people, I wanna kill more Muslims", he told BBC TV.
The van swerved towards the people outside the Finsbury Park Mosque in north London just as they began to assist the man, who had collapsed.
Those with an eye on London's recent history will be aware that Finsbury Park Mosque was seen as a hotbed of Islamic radical preaching by Abu Hamza.
It is located a short walk away from Emirates Stadium, home of the Arsenal football club in north London.
The incident is being investigated as a terrorist attack and has been referred to as such by UK Prime Minister Theresa May.
Jeremy Corbyn, the leader of the Labour Party and the local member of parliament for the area said on Twitter he was "totally shocked". Police shot and killed the three men who carried out the attack. In March, a lone attacker drove his auto into people on Westminster Bridge, then fatally stabbed a police officer at the gates of Parliament.
It also follows a suicide bombing at a pop concert in Manchester, northern England, in May which killed 22, while in March, a man drove a rented vehicle into pedestrians on Westminster Bridge in London and stabbed a policeman to death before being shot dead.