The Metropolitan Police confirmed that the 48-year-old man has been arrested on suspicion of attempted murder.
Another witness, Abdikadar Warfa, said he helped to detain the suspect while his friends helped victims. Police said a man who was driving the vehicle has been arrested and taken to a.
"When he went into the [police] van he made gestures, he was laughing".
- Eight people were hospitalized, all Muslim.
A member of staff at Pontyclun Van Hire said the company would not be issuing a statement.
"This was a van driven into a crowd of people who were tending a man who was already injured and they were coming home from night-time prayers in the mosque".
He has been taken to hospital as a precaution and is due to receive a mental health assessment. Two other people were treated at the scene for minor injuries but walked away.
"Hatred against Muslims is unacceptable as well", Miqdaad Versi, assistant secretary general of the Muslim Council of Britain, told Sky News.
Police believed that the attacker acted alone, despite earlier reports from witnesses, who had said they saw two other people flee the scene.
Mr Corbyn said that, while he had not spoken to the Prime Minister directly, their offices had been in touch, and Theresa May "expressed her condolences for the death and also concerns about what happened last night".
The mayor of London, Sadiq Khan, said extra police had been deployed to reassure communities, especially those observing Ramadan.
"Our community is in shock", he said, urging people attending prayers to remain vigilant, a warning that was echoed by police.
The use of a vehicle to mow down pedestrians drew horrifying parallels with the London Bridgeattack, when three men drove a van into pedestrians before embarking on a stabbing spree, as well as with another auto and knife rampage in Westminster in March.
Monday's attack is the third in London since March involving a vehicle as a weapon against pedestrians.
Dead: As of Monday morning, the person killed had not been identified. Basu said it was a "challenging" time for London and that the emergency services were stretched.
London Ambulance tweeted: "We have sent a number of resources to an incident in Seven Sisters Road".
"He waited until people had come out then drove at the people on the right then swerved to hit people on the left. He was fighting to run away".
- The Prime Minister said police chose to treat the incident as a terror attack within eight minutes of receiving the first emergency call.
Bystanders rushed to pin down the driver of the rented van and held him until the police arrived.
"He said, 'I'd do it again, '" Rana told The Washington Post.
"Yes we do have to tackle extremism and radicalisation but we can't actually see that this is one and the same", he said. CNN spoke to a man at the company, who said he was the owner but declined to give his name.
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. He complained that the "mainstream media" was unwilling to call the attack a terrorist incident for many hours.
He said: "During the night, ordinary British citizens were set upon while they were going about their lives, completing their night worship".
"It is particularly disconcerting as it seemed to be particularly targeted at worshippers just finishing their prayers during the holy month of Ramadan. Mosque safety needs to be stepped up and this includes entry and exit points", it said in a statement.
Muslims pray on a sidewalk in the Finsbury Park area of north London after a vehichle hit pedestrians, June 19, 2017.
Amid the angry screaming, people are heard trying to calm the crowd, one man saying: "Don't worry, officers are here".