'What A Mad World': Shock Gives Way To Defiance In Parliament After Attack

British lawmakers reacted with defiance, shock and emotional tribute on Thursday as they came to terms with an attack which left a police officer dead on the cobbles inside the gates of the world's oldest parliament.

"What a mad world," said Tobias Ellwood, a government minister and former soldier who walked away from the scene on Wednesday with blood on his face and hands after joining unsuccessful attempts to revive policeman Keith Palmer.

Palmer was one of three killed by a lone attacker who ploughed a vehicle into tourists on a bridge and then ran through the gates of parliament armed with a knife. The attacker was shot dead by armed police officers.

The attack was the worst on British soil since 2005, when 52 people were killed by Islamist suicide bombers on London's public transport system, and the most serious breach of the parliamentary estate in decades.

"A terrorist came to the place where people of all nationalities and cultures gather to celebrate what it means to be free, and he took out his rage indiscriminately against innocent men, women and children," Prime Minister Theresa May told lawmakers.

Parliament re-opened as normal on Thursday, although members and staff had to navigate police cordons extending hundreds of metres out from the 19th century Gothic palace on the banks of the River Thames.

"This was a horrific crime and it has cost lives and caused injury but as an act of terror it has failed," said Labour Party lawmaker Harriet Harman. "It has failed because we are here and we are going to go about our business."

May addressed a packed chamber to deliver a speech praised by lawmakers from all parties as the normal adversarial tone of debate was replaced with one of sombre unity.

"The streets are as busy as ever. The offices full. The coffee shops and cafes bustling," May said.

"It is in these actions - millions of acts of normality - that we find the best response to terrorism."

"Huge Professionalism"

May said she had spoken to Ellwood after the attack and praised his "huge professionalism".

Straight-faced, leaning against a row of seats at the back of parliament, he nodded in acknowledgement at a steady stream of tributes.

"I was on the scene and as soon as I realised what was going on I headed towards it," Ellwood, 50, said in comments reported by the Times newspaper.

"I tried to stem the flow of blood and give mouth-to-mouth while waiting for the medics to arrive but I think he had lost too much blood. He had multiple wounds, under the arm and in the back."

Tributes also poured in for the 48-year old police officer, another former soldier who had spent 15 years working in parliament. At 0933 GMT staff and police officers throughout the building stood for a minute's silence in his honour.

"He was a strong, professional public servant," said James Cleverly, a lawmaker who had known him for 25 years and struggled to hold back tears as he stood to speak in parliament.