London police say a 47-year-old man has been arrested on suspicion of commission, preparation or instigation of terrorism including murder and attempted murder after a car ploughed into a crowd of pedestrians near a north London mosque.
The man, who is in custody at a south London police station, was arrested earlier on suspicion of attempted murder.
The BBC reports it understands the man in 47-year-old Darren Osborne from Cardiff.
The Metropolitan Police said in a statement that the man was detained by members of the public at the scene of the attack early Monday.
Authorities say a residential area in Cardiff, Wales, is also being searched.
Deputy Assistant Commissioner Neil Basu says: "This is being treated as a terrorist incident and is being investigated by the Counter Terrorism Command."
Eight people remain in hospital after the incident.
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