The terror network reportedly claimed a "detachment" of its fighters crashed a rented van into a crowd of people on London Bridge before going on a stabbing rampage Saturday night, killing seven people and wounding nearly 50 others. However, ISIS gave no evidence to back up its claim.
Earlier on Sunday, British Prime Minister Theresa May condemned the "evil ideology" behind the London attacks.
May addressed the attacks Sunday after a meeting of the government's COBRA emergency committee. She called for a tougher stance against extremists and tougher controls on cyberspace to prevent its use by extremists.