According to Sky News, further arrests could be made related to a suicide bomb attack in Manchester that killed 22 people at a pop concert in May.
Members of the Sikh Sewa Organisation, which provides meals for the homeless, said they had to flee for “their own safety” after far-right activists became “abusive” towards them.
Militants drove a van at high speed into pedestrians on London Bridge before stabbing Saturday night revellers on the street and in nearby bars.
May said it was possible a wider group was linked to the bombing at Manchester, prompting the increase in security few weeks before the elections.
“One of the soldiers of the Caliphate was able to place an explosive device within a gathering of the Crusaders in the city of Manchester,” ISIS said.
No militant group has so far claimed responsibility for the attack in which at least 22 people were killed but ISIS supporters celebrated on social media.