The prime minister says the UK cannot continue as before and “it is time to say enough is enough”, after seven people were killed and 48 others injured in a terror attack in London.
A white van hit pedestrians on London Bridge at about 22:00 BST on Saturday, then three men got out and stabbed people in nearby Borough Market.
The three attackers, who wore fake bomb vests, were shot dead by police.
Mrs May said the UK’s counter-terrorism strategy would be reviewed.