Terrorist rampage: London terror attacker's car speeding along the pavement of Westminster Bridge as one terrified woman JUMPS into the River Thames
Investigation gathers pace
(From CNN report) Mark Rowley, the lead officer in the UK for counter-terrorism policing, said hundreds of detectives worked through the night. Their investigation focused on the attacker's motivation, preparation and associates, he said.
"It is still our belief -- which continues to be borne out by our investigation -- that this attacker acted alone yesterday and was inspired by international terrorism," he said. "To be explicit, at this stage, we have no specific information about further threats to the public."
It was the first mass-casualty terrorist attack in Britain since 2005, when 52 people and four attackers died in the July 7 bomb attacks
on the London public transportation system.
Rowley told journalists late Wednesday that police believe Wednesday's attack was an act of "Islamist-related terrorism," and indicated they knew the identity of the assailant but were not releasing his name.
Overnight, officers from the Metropolitan Police searched addresses in the city of Birmingham, in central England, and elsewhere and made a number of arrests, West Midlands Police said. "The arrests and searches were intelligence-led and there was no immediate risk to public safety," a statement said.
A UK official told CNN the working theory was that the attack was ISIS "inspired or copycat".