Mark Rowley the national lead for Counter Terrorism Policing in London says a full investigation is underway following an attack on Parliament which left four people dead and 20 people injured.
Acting Deputy Commissioner Rowley said, "We have an ongoing operation - and whilst we currently believe there was only one attacker - I am sure the public will understand us taking every precaution in locking down and searching the area as thoroughly as possible.”
Authorities have declared the event a “terrorist incident” and say it began when a car had driven over Westminster Bridge, hitting and injuring a number of people.
Rowley said among those hit were “three police officers who were on their way back from a commendation ceremony.”
He went on to say, “The car then crashed near to Parliament and at least one man – armed with a knife – continued the attack, trying to enter Parliament."
Police confirmed four people had died which included a policeman who was “protecting Parliament from the attack and the man police believe to be the attacker was shot by a police firearms officer.”
"This investigation has the full weight and expertise of the Counter Terrorism Command behind it. If there are people who saw the events unfold but haven't yet spoken to police please get in touch with us.
"A crime scene will remain in place in the affected areas in Westminster - it is vital that we carry out a painstaking investigation to recover all possible evidence," Rowley concludes.