Prince William, his wife Kate and his brother Prince Harry spoke with survivors and the families of those killed in the terror attack outside the British parliament at a memorial service on Wednesday.
The royals joined those affected by the assault at a "Service of Hope" at Westminster Abbey, just across Parliament Square from the scene of the attack on March 22.
The assault killed four people, including a police officer guarding the gates of parliament.
Khalid Masood, a 52-year-old convert to Islam known to the security services, drove into pedestrians on Westminster Bridge before stabbing policeman Keith Palmer to death. Masood was later shot and killed by officers in the parliament's forecourt.
Leslie Rhodes, 75, a retired window cleaner; Aysha Frade, 44, a school administrator; and Kurt Cochran, 54, an American tourist, were killed on the bridge.
Cochran's wife Melissa attended the service in a wheelchair, having suffered a broken leg and rib and a cut head in the attack.
William, second in line to the throne, laid a wreath at the Innocent Victims' Memorial outside the abbey.
During the service, he read the parable of the Good Samaritan from the Bible.
London Mayor Sadiq Khan and Home Secretary Amber Rudd, the interior minister, also gave readings.
Witnesses and emergency service workers involved in the response effort were among the 1,800 people who attended, along with the speakers of both houses of parliament.
The injuries were still evident for some victims, many of whom arrived on crutches, with their legs in plaster or with visible wounds.
John Hall, the Dean of Westminster, led the service, telling the congregation that the attack had left people "bewildered and disturbed".
He said it was "likely that we shall never know" Masood's motivation for the attack.
After the service, the royals met privately with survivors and the families of those killed.
Twelve people arrested in connection with the attack have all been released and face no further police action.
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