British police say they have arrested 12 people in east London over the attack in the London Bridge area.
Police said in a statement that the arrests were made Sunday morning in Barking by counterterrorism officers.
Officials said that seven people died in the Saturday night attack and roughly 48 were wounded. A British Transport Police officer and an off-duty officer were among the injured. In addition, three attackers were shot dead by police.
Police say the investigation is progressing rapidly. Prime Minister Theresa May has blamed Islamic extremists.
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