Victims of the Westminster terror attack have been remembered at a special vigil.
The ceremony in Westminster Hall was held to mark the first anniversary of the atrocity and was attended by politicians, senior police officers and survivors.
Five people were killed, including Police Constable Keith Palmer, and dozens of others were injured when 52-year-old Khalid Masood launched a car and knife attack on Westminster Bridge and the Palace of Westminster before he was shot dead.
Pc Palmer's name will be one of 1,400 inscribed on the new UK Police Memorial being built in Staffordshire.
Archbishop of Canterbury Justin Welby told the gathering: "Darkness struck across Westminster Bridge and in this palace. It spread across the bridge like a snake, driving to the left and right, killing and harming."
The Rev Rose Hudson-Wilkin added: "A year ago today on this estate and on Westminster Bridge we were visited by what I regard as evil."
She praised Pc Palmer, saying he "ran towards the danger in order that we might be safe".
Victims of the rampage were Pc Palmer (48), who was on duty at the Palace of Westminster, US tourist Kurt Cochran, Romanian tourist Andreea Cristea (31) and Britons Aysha Frade (44) and 75-year-old Leslie Rhodes.
Earlier in the day MPs observed a minute's silence as Speaker John Bercow asked members in the House of Commons chamber to pause "in respectful memory" of those who were killed that day.
Prime Minister Theresa May was not at the Westminster Hall service because she was attending an EU summit in Brussels.
Downing Street said that she attended an earlier private service held in the Palace of Westminster.
A Government minister who was hailed a hero after the attack told BBC Radio 4's Today that the UK is going through a "dark chapter" facing the terrorist threat.
Tobias Ellwood, who tried in vain to save the life of Pc Palmer, paid tribute to the police for their work in a country "that seems to be getting more dangerous and more volatile".
Defence Minister Gavin Williamson said the threats faced by the UK were not going away and involved not just terrorism but "resurgent nations challenging the world order".