British police have classified the attack at a synagogue in Manchester as a terrorist attack and have arrested two people.
National Counter-Terrorism Chief Lawrence Taylor said the identity of the attacker is known to police but will not be released pending further investigation.
He said patrols have been stepped up across the country.
British police have confirmed that three people have died in the attack, including the attacker, who was killed in a clash with security forces.
The attack took place when a man drove a car into a crowd and then attacked people with a knife outside a synagogue in Manchester.
