British police said on Sunday they would release the names of the three men who killed seven people in London "as soon as operationally possible", adding that searches were continuing in four properties.
The men rammed a van into pedestrians and stabbed revelers on Saturday night before being shot by police. Twelve people were arrested in east London on Sunday in connection with the attack.
Police said that one man had been released without charge, but four men and seven women were still being detained under terrorism legislation.
"The public can expect to see additional police - both armed and unarmed officers - across the capital as you would expect in these circumstances," Mark Rowley, Britain's top counter-terrorism policeman, said in a statement.