The person spoke on condition of anonymity because he was not authorized to speak about the ongoing investigation into an attack on worshippers outside a mosque in London.
Some members of the community suggested in the aftermath of Monday's Finsbury Park attack - which left one man dead and 10 injured - that it was not handled the same way as the attacks on London Bridge and Westminster attacks earlier this year.
One man was trapped under the van and people tried to lift up the vehicle to free him.
The Metropolitan Police confirmed that the 48-year-old man has been arrested on suspicion of attempted murder. Police are investigating whether a man who died while being given first aid at the scene was killed by the attack or something else.
The incident comes just over two weeks after three Islamist militants drove into pedestrians on London Bridge and stabbed people at nearby restaurants and bars, killing eight.
"An attack on a mosque, an attack on a synagogue, an attack on a church is actually an attack on all of us".
"We must all continue to stand together, resolute, against all those who try to divide us and spread hate and fear", Rudd said.
Police said all the victims of the attack, which was in the area of Finsbury Park Mosque, were Muslim. Basu said: "I would like to thank those people who helped police in detaining the man and worked with officers to calmly and quickly get him into our custody".
Trump lawyer says Trump not under investigation, despite Trump's tweet
Sekulow: No, Chris... let me crystal clear so you completely understand. Wallace: But you just said two times that he's being investigated.
"From the window, I started hearing a lot of yelling and screeching, a lot of chaos outside..."
The group's general secretary, Harun Khan, said that eyewitnesses saw the van driver hit a number of Muslims.
The video, shot by a man passing by a couple of minutes after the attack happened, shows the chaos at the scene as people tended to the injured until the emergency services arrived.
The driver of the van in Monday morning's attack was arrested after he was seized and prevented from fleeing by bystanders; a Muslim imam reportedly prevented the crowd from injuring the attacker.
"This big van just came and went all over us", witness Abdulrahman Saleh Alamoudi told BuzzFeed News. "He did what he did deliberately to hit and kill as many Muslims as possible, so he is a terrorist". The attack was targeted against a crowd leaving the Finsbury Park mosque after Ramadan prayers.
The German government is also offering its condolences.
The British Muslim Council (MCB) has described the incident as a "violent manifestation of Islamophobia". "While this appears to be an attack on a particular community", he said, "like the bad attacks in Manchester, Westminster and London Bridge it is also an assault on all our shared values of tolerance, freedom and respect". In March, a man drove a vehicle into pedestrians on Westminster Bridge and stabbed a police officer to death before being shot dead.
Manchester was hit by a deadly attack on May 22 when a suicide bomber killed 22 people at an Ariana Grande concert.
In the span of a few months, Britain has suffered from three major terrorist attacks.