Earlier, a vehicle rammed into crowd nearby a mosque in Seven Sisters Road, located near the Finsbury Park station in north London.
"One man was pronounced dead at the scene…Eight people injured were taken to three separate hospitals; two people were treated at the scene for minor injuries. At this stage there are no reports of any persons having suffered any knife injuries," the police said.
London police said that the 48-year-old van driver had been found at the scene detained by members of public. He will be a subject of a mental health assessment in due course, the police added.
"He has been taken to hospital as a precaution, and will be taken into custody once discharged. He will also be subject of a mental health assessment in due course," the police added.
UK Prime Minister Theresa May said later that the incident was being treated as a potential terrorist attack.
"Police have confirmed this is being treated as a potential terrorist attack," May said. "I will chair an emergency meeting later this morning."
The investigation into the matter will be conducted by counter-terrorism command, the police said.
Earlier, the police said it was "too early" to say whether the incident was a terrorist attack.