Five people have died and at least 40 have been injured in the terror attack in London yesterday.
The rampage by a knifeman at Westminster began on Wednesday (March 22), when he mowed down pedestrians on Westminster Bridge before stabbing to death a policeman inside the gates of Parliament before being shot dead by other officers.
The dead officer has now been named as PC Keith Palmer, 48, a husband and father.
PM Theresa May said the attack was "sick and depraved" and struck at values of liberty, democracy and freedom of speech.
The attacker has not been named by police.
Whitby MP and immigration minister Robert Goodwill said he was coming out of the voting chambers when the lockdown was put in place.
He said: "This is a terrible incident on the state of our democracy and our way of life.
"My heart goes out to those who were injured and to the friends and family of those who were killed.
"The prime minister is absolutely right that we must never bow down to this type of violent extremism and the fact that parliament will sit again today is a motion of the defiance that we must always show when faced with this twisted extremism."
A minute of silence will be held in Parliament at 9.30am this morning.
Commenting on the day’s events, Dave Jones, the Chief Constable of North Yorkshire Police said: "By now many people will have seen news coverage of the attack that took place at Westminster earlier today. I would like to reassure the public that there is no intelligence to suggest that there has been any change in the level of risk here in North Yorkshire.
"Nevertheless, in line with other police forces, we will continue to keep our contingency planning under close review, and make careful assessments of the security around any special events.
"On behalf of North Yorkshire Police I would like express my deepest sympathy to those who have lost loved ones, or who have suffered as a result of this attack. Our thoughts are with those people, and with our colleagues in the Metropolitan Police and other emergency services at this difficult time.”