Relatives of those killed in the Westminster terror attack have joined members of the Royal Family at a "service of hope" at Westminster Abbey.
Khalid Masood killed three people when he drove into crowds on 22 March and stabbed a policeman to death before being shot dead at the UK Parliament.
Emergency services staff were among the 2,000-strong multi-faith congregation.
Melissa Cochran, whose husband died in the attack, said the service was "the most beautiful thing I've ever seen".
"My husband was a big fan of cathedrals and he would have very much liked to have seen that place - it was beautiful," she added.
She said: "The support of my family and the outpouring of love from everyone has given me the strength to to do what I have to do. My husband would want me to continue and wouldn't want me to not move forward as quickly as possible."
Mrs Cochran was seriously injured during the attack which left her with a broken leg, broken ribs and head injuries.
"Kurt was probably the best man I've ever met. He was sweet and kind and I'm extremely proud of him. I'm very happy that the world now knows what a wonderful man he was", she added.
'It crushed me'
Speaking to the BBC, Mrs Cochran said she could recall "the panic of not being able to see my husband anywhere" and the moment she found out her husband had died.
"It was after the surgery on my leg, I had come out of recovery and they placed me in a hospital room. My parents had come to visit and were there waiting for me when I came out and I had asked them to find out what had happened to my husband.
"Previously to that no-one could tell me... no-one had any information. My parents walked out of the room and came back in.
"Both grabbed my hand and said that he didn't make it, which crushed me."
Addressing the congregation earlier, the Dean of Westminster, the Very Reverend John Hall praised the unity of Londoners and Britons in the aftermath of the attack.
He said: "We stand together just as in this service the world faiths are represented and we will pray together above all for the gift of hope.
"Our prayer and commitment is to live together peacefully and respectfully rich in our diversity and to sing together in harmony."
However, he said the attack had left the nation "bewildered".
He added: "What could possibly motivate a man to hire a car and take it from Birmingham to Brighton to London, and then drive it fast at people he had never met, couldn't possibly know, against whom he had no personal grudge, no reason to hate them and then run at the gates of the Palace of Westminster to cause another death? It seems likely that we shall never know."
'Best of humanity'
Labour MP Mary Creagh said the mood at the service was both sombre and resolute.
She said: "We saw the worst of humanity with the terror attack... but we also saw the best of humanity, coming together, and we saw that again today, in renewed resolution, and solidarity with the families."
The Dean invited members of the congregation to light candles to honour the commitment. Prince William lit the first candle and the light was passed around to people at the service.
Home Secretary Amber Rudd gave the first reading at the service from Jeremiah 31: 15-17, reflecting the service's theme of hope. The second reading was made by Prince William, who told the story of the Good Samaritan.
The service also included a reading by London Mayor Sadiq Khan.
Other speakers included Met Police Commander Mak Chishty, Rabbi Baroness Julia Neuberger DBE, Ayatollah Sayyid Fadhel Hosseini Milani, PC Jaskaran Garcha and the Reverend Anthony Ball.
Those who died in the attack were Aysha Frade, 44, who worked at a London sixth-form college; American tourist Kurt Cochran, 54, from Utah; retired window cleaner Leslie Rhodes, 75, from south London; and father-of-two PC Keith Palmer, 48.
It is the first time members of all their families have come together in the same place.
Commons Leader David Lidington and Met Police Acting Commissioner Craig Mackey were also there.