Defiant MPs stood side by side in silence as they came together to remember those injured and killed in the Westminster attack.
With the benches full and heads bowed, the debating chamber usually full of noise observed a minute of silence.
It occurred at 9.33am with Pc Keith Palmer, 48, a father and husband killed in the attack, having the shoulder number of 933.
Speaker John Bercow said: "Colleagues, in respectful memory of those who lost their lives in yesterday's attack and of all of the casualties, we shall now observe a minute's silence."
International Trade Secretary Liam Fox added: "As we begin our questions today, I think it's appropriate we recommit ourselves to the values this Parliament represents.
"Those who carry out such wicked and depraved acts as we saw yesterday can never triumph in our country and we must ensure it is not violence, hatred or division but decency and tolerance that prevails in our country."
MPs said "hear, hear" at the end of Mr Fox's comment.
Conservative Bob Blackman, MP for Harrow East, was visibly emotional as he made a short comment about the attack before asking a question to Mr Fox with the Commons continuing with its scheduled questions session on international trade.
Mr Blackman said to Mr Bercow: "Can I join with you and my right honourable friend in expressing sincere condolences for the victims of the terrible atrocity yesterday and in particular to the family of Pc Keith Palmer, who died so that we can carry out our democratic duties?"
Some MPs clutched tissues while others stared at their phones as the chamber understandably lacked the usual cheers and shouts that accompany debates.
The public gallery remained open with the "business as usual" mantra coming from the doorkeepers who look after those visiting the Commons.
Around a dozen or so people watched the early exchanges of Thursday's business.
Several bunches of flowers have been laid in Westminster Hall alongside what appeared to be a book of condolence.
They were left in a small, roped-off area in what is the oldest part of the building of Parliament.
Mr Bercow later confirmed to MPs that books of condolence would be placed in the library of the House and also in Westminster Hall.
He told the Commons: "After yesterday's shocking events, I know that the whole House will want me to express our heartfelt condolences to the families and friends of the victims of this outrage.
"A police officer, Pc Keith Palmer, was killed defending us, defending Parliament and defending parliamentary democracy.
"Arrangements have been made for books of condolence in the library and Westminster Hall.
"Our hearts go out to all those directly and indirectly touched by yesterday's events.
"I should like to thank all colleagues, staff of the House and members' staff for their forbearance in very stressful circumstances yesterday."
French foreign minister Jean-Marc Ayrault visited the Commons and sat in the side public gallery overlooking the Prime Minister as she delivered a statement condemning the terror attack.
He stood up and nodded to the MPs below as Mr Bercow informed politicians he was in the gallery.
Three French schoolchildren were injured in the attack.
Mr Bercow said: "Sir, we appreciate your presence and your very fitting display of solidarity with us."
A packed House of Lords also stood for a minute's silence before the public and press were admitted at the start of the day's traditional prayers.