Emergency services staff and forensic officers work on Westminster Bridge in London, Britain on March 22, 2017. (Xinhua/Tim Ireland)
LONDON, March 23 (Xinhua) -- Britain's Houses of Parliament resumed business Thursday, less than 24 hours after a terrorism attack, starting the day with a minute's silence in the House of Commons.
Prime Minister Theresa May, flanked by her senior cabinet members, was in a packed House of Commons chamber to observe a minute's silence.
As politicians and managers at Westminster reflected on the attack which left four people dead, detectives continued their probe into the life and motive of the lone terrorist.
He was shot and killed minutes after he stabbed unarmed officer, Constable Keith Palmer, who was on duty guarding the Houses of Parliament. Palmer died despite heroic efforts to save his life.
A further 36 people were injured, most of them in an incident minutes earlier on Westminster Bridge when a car driven by the terrorist ploughed into a crowd of innocent pedestrians.
Hundreds of detectives worked throughout the night on the inquiry leading to swoops on a number of addresses, mainly in Birmingham, Britain's second biggest city, 200 kilometers north of London. Reports revealed that seven people had so far been arrested and brought in for questioning by police.
At Scotland Yard, headquarters of London's Metropolitan Police, Acting Deputy Commissioner Mark Rowley, confirmed that the four dead were Constable Palmer, the terrorist, a woman in her mid-40s and a man in his mid-50s.
Rowley said: "Hundreds of detectives have been working through the night and during that time I can confirm we have searched six addresses -- and made seven arrests. The inquiries in Birmingham, London and other parts of the country continue.
"It is still our belief -- which continues to be born out by our investigation -- that this attacker acted alone yesterday and was inspired by international terrorism.
"To be explicit -- at this stage, we have no specific information about further threats to the public.
"Clearly our investigation is ongoing -- developing all the time -- and is focused on his motivation, his preparation and associates."
Large areas of London around Westminster and Whitehall, continue to be sealed off after being declared a crime scene.
Rowley added: "As people are out and about on the streets of the capital this morning they will see more police officers on duty -- armed and unarmed -- and a mix of British Transport Police and the City of London Police."
London Mayor Sadiq Khan announced there would be a vigil in Trafalgar Square, just a few hundred meters from the Houses of Parliament, at 6 p.m. Thursday local time.