Constable Keith Palmer "left for work [Wednesday] expecting to return home at the end of his shift and had every right to expect that would happen."
Prime Minister Theresa May said that the 'working assumption is that the attacker was inspired by Islamist ideology.'
Metropolitan Police's Mark Rowley gave more details about investigations into the man who attacked the UK Parliament.
Rescue workers rushed wounded civilians to hospital following an attack outside the UK Parliament.
A truck hit pedestrians on Westminster Bridge before crashing into a railing, and a police officer was fatally stabbed near the House of Commons.