In the third major militant assault to hit Britain in less than three months, attackers rammed a van into pedestrians on London Bridge before stabbing revelers in nearby bars.
British Prime Minister Theresa May will chair a meeting of the government's emergency response committee Monday to discuss the response to the attack which comes ahead of a national election Thursday, Reuters reported.
Police had already arrested 12 people in the Barking district of east London over the weekend and they said Monday they had entered two premises in Newham and Barking at 0315 GMT and detained "a number of people". They said searches were ongoing at both addresses.
The Daesh (ISIL or ISIS) terrorist group has claimed responsibility for the terror attack through its Amaq 'news agency'.
A statement on the group's propaganda outlet said a “detachment” of its fighters had carried out the atrocity.