British police said it was too early to say whether a death near a mosque in north London on Monday was due to an attack by a van driver who ploughed into worshippers.
"The attack unfolded as a man was already receiving first aid at the scene, sadly that man has died," Neil Basu, senior national co-ordinator for counter-terrorism policing, said.
"Any causative link between his death and the attack will form part of the investigation. It is too early to say if his death was as a result of this attack."
Basu also said it was too early to say what the motive of the attacker might have been was but that the incident had all the hallmarks of a terrorist attack and that all the victims were Muslim.
He said no other suspects had been identified and that the police had seen no evidence of an earlier reported knife attack at the scene.