The man detained at the scene of an attack in Finsbury Park, north London, last night has been arrested on terror offences, Scotland Yard said this afternoon.
The 47 year-old man, who was arrested on suspicion of murder this morning, was further arrested on suspicion of the commission, preparation or instigation of terrorism including murder and attempted murder.
Police appealed for witnesses after one man died and several others were injured when a van was driven into a crowd of pedestrians outside the Finsbury Park Mosque in the early hours of this morning.
The man suspected of being the driver was detained at the scene by members of the public.
"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. Their restraint in the circumstances was commendable," said deputy assistant commissioner Neil Basu, the senior national coordinator for counter terrorism.
"This investigation is ongoing, and we are working fast to know the full details of how and why it took place."
Met Police commissioner Cressida Dick said: "London has woken up to the news of another appalling attack on our city. My thoughts are with the family of the man who has died and with all those who were injured.
"My officers were on the scene almost immediately, and other uniformed and specialist officers quickly arrived to support them. They worked quickly with colleagues from the other emergency services to treat the injured.
"I want to thank all those members of the public who assisted police and emergency services in our task."
Dick added that an ongoing investigation has been established by the counter terrorism command to establish why the attack was carried out.
"London is a city of many faiths and many nationalities. An attack on one community is an attack on all of us."
"Terrorists will not succeed in their attempts to divide us and make us live in fear," she continued.
"Extra officers are on duty in the area to help reassure the local community. They will be there for as long as they are needed.
"Communities will see additional officers patrolling across the city and at Muslim places of worship. We are working as hard as we can to protect all our communities, and we will not be defeated."